Domain 5: Network Troubleshooting and Tools Flashcards
1
Q
Which of the following troubleshooting steps involves prioritizing trouble tickets based on the severity of the problem?
A. Identify the problem
B. Establish a theory of probable cause
C. Test the theory to determine cause
D. Establish a plan of action to resolve the problem and identify potential effects
E. Implement the solution or escalate as necessary
F. Verify full system functionality and, if applicable, implement preventive measures
G. Document findings, actions, and outcomes
A
A. Identify the problem
The first step in troubleshooting is to identify the problem by establishing symptoms related to the network issue being reported. In this step, problems are typically reported as trouble tickets, which are prioritized based on the severity of the problem. You complete the other steps after the trouble ticket has been prioritized and is being investigated.
2
Q
Which of the following is considered a system-wide error?
A. A problem with an order entry or customer service call center resource
B. A problem with a router that affects only one local area network (LAN)
C. A fatal error that causes a single computer to fail
D. A problem with an email server that affects all network users
A
C. A fatal error that causes a single computer to fail
A system-wide error is a problem that renders an individual user’s system (computer) completely unusable. All the other problems listed would affect more than one system or user.
3
Q
Which of the following is a network-wide problem?
A. A problem with an order entry or customer service call center resource
B. A fatal error that causes a single computer to fail
C. A problem with an application server that affects a single local area network (LAN)
D. A problem with a router that connects an entire network to the Internet
A
D. A problem with a router that connects an entire network to the Internet
Any problem that affects all the users on the network is a network-wide problem and should be given the highest priority. An example of this would be a problem with an Internet router. All other problems listed do not affect the entire network.
4
Q
A user reports that she can’t connect to a server on her network. Ed wants to identify the scope of the problem, so he tries to reproduce the problem on the user’s computer. The problem still remains. No other users are reporting this problem. What is the next logical step that Ed should perform to identify the affected area?
A. Verify that the local router is forwarding traffic
B. Try performing the same task on a computer attached to the same segment
C. Verify that the server is configured properly
D. Verify that the switch the client is connected to is functioning
A
B. Try performing the same task on a computer attached to the same segment
In this scenario only one user is reporting a problem. Therefore, the likeliest next step is to perform the same task on another computer attached to the same segment. If Ed can perform the task successfully, the problem most likely lies within the user’s computer or the connection to the switch. Since no other users are reporting the same problem, the server and switches on the network are probably up and functioning. Checking the router isn’t necessary since the user and server are on the same network.
5
Q
Which of the following troubleshooting steps involves asking the user preliminary questions such as, “What were you doing when the problem occurred?”
A. Identify the problem
B. Establish a theory of probable cause
C. Test the theory to determine cause
D. Establish a plan of action to resolve the problem and identify potential effects
E. Implement the solution or escalate as necessary
F. Verify full system functionality and, if applicable, implement preventative measures
G. Document findings, actions, and outcomes
A
A. Identify the problem
The first step in troubleshooting is to identify the problem by establishing symptoms related to the network problem being reported. In this step you ask the user many questions to identify and define the symptoms of the problem and prioritize the trouble ticket. Although you might continue to ask the user questions throughout the troubleshooting process, this is typically associated with the first step of the troubleshooting process.
6
Q
When troubleshooting, you begin by taking steps to identify the problem. After you do this, which of the following steps should you perform next?
A. Implement the solution
B. Establish a plan of action
C. Establish a theory of probable cause
D. Verify full system functionality
A
C. Establish a theory of probable cause
After identifying the problem, the next step is to establish a theory for the probable cause of the problem. After that, you can test your theory, establish a plan of action, implement a solution, verify the functionality of the system, and document the entire process.
7
Q
In which troubleshooting step do you try to duplicate a network problem to “divide and conquer” by logically and methodically eliminate elements that aren’t the source of the problem?
A. Identify the problem
B. Establish a theory of probable cause
C. Test the theory to determine cause
D. Establish a plan of action to resolve the problem and identify potential effects
E. Implement the solution or escalate as necessary
F. Verify full system functionality and, if applicable, implement preventative measures
G. Document findings, actions, and outcomes
A
B. Establish a theory of probable cause
The second step in troubleshooting is to attempt to duplicate a problem and develop a theory of its probable cause. As you troubleshoot a problem, you then test your theory to confirm your findings. You complete the other troubleshooting steps after the specific cause has been identified.
8
Q
You have a problem with a server or other network component that prevents many users from working. What type of problem is this?
A. A network-wide problem
B. A shared resource problem
C. A system-wide problem
D. A user application problem
A
B. A shared resource problem
If a problem lies within a specific server or other network component that prevents many users from working, it is a shared resource problem.
9
Q
A single Windows user suddenly can’t connect to any hosts on the network (local or remote). Alice interviews the user and finds out that he made some changes to his computer’s Internet Protocol (IP) configuration properties. What should she do next?
A. Run the ipconfig command to view the local configuration
B. Check the Domain Name System (DNS) server to see if it is resolving IP hostnames
C. Check the Windows Internet Name Service (WINS) server to see if it is resolving Network Basic Input/Output System (NetBIOS) names
D. Verify that the router is functioning
A
A. Run the ipconfig command to view the local configuration
Since only one user is reporting the problem and he had admitted to making changes to his IP configuration, Alice should probably start by checking the configuration using the ipconfig command.
10
Q
Alice has a network with a Domain Name System (DNS) server, a proxy server, and an Internet router. A user is complaining that she suddenly can’t connect to hosts on her own local area network (LAN) and other internal LANs, and she can’t access hosts on the Internet. What is the likeliest problem?
A. The user’s local configuration
B. The proxy server
C. The DNS server
D. The router
A
A. The user’s local configuration
Since only one user is reporting the problem, the user’s computer and its configuration are the likeliest suspect components. ADNS, proxy, or router problem would affect more than one user.
11
Q
Alice is working the help desk when a user calls and reports that she is unable to connect to the Internet. Which of the following steps is the one Alice is least likely to perform first when troubleshooting the problem?
A. Check the configuration of the router connecting the LAN to the Internet.
B. Ask the user if she can access resources on the local network.
C. Check to see if anyone else is experiencing the same problem.
D. Check the user’s job title to see if she is an important person in the company.
A
A. Check the configuration of the router connecting the LAN to the Internet.
There are many possible causes for the problem that are more likely than a router configuration error, so this is not something Alice would check first. Asking if the user can access the local network attempts to isolate the problem. If she cannot, the problem could be in her computer; if she can, then the problem lies somewhere in the Internet access infrastructure. If other users are experiencing the problem, then the issue should receive a higher priority, and Alice knows that the problem does not lie in the user’s computer. While it might not be the first thing she checks, it is a political reality that higher ranking users get preferential treatment.
12
Q
In the standard troubleshooting methodology, which of the following steps appears last but must actually be practiced throughout the troubleshooting process?
A. Test the theory to determine cause
B. Document findings, actions, and outcomes
C. Verify full system functionality and, if applicable, implement preventive measures
D. Implement the solution or escalate as necessary
E. Establish a plan of action to resolve the problem and identify potential effects
F. Establish a theory of probable cause
G. Identify the problem
A
B. Document findings, actions, and outcomes
Documenting everything you discover and everything you do is a crucial part of the troubleshooting method that must begin before you take any other action whatsoever. However, it appears as the last step in the troubleshooting methodology.
13
Q
In which troubleshooting step is a trouble ticket created?
A. Establish a theory of probable cause
B. Verify full system functionality and, if applicable, implement preventive measures
C. Implement the solution or escalate as necessary
D. Test the theory to determine cause
E. Identify the problem
F. Document findings, actions, and outcomes
G. Establish a plan of action to resolve the problem and identify potential effects
A
E. Identify the problem
The first step in troubleshooting involves identifying the problem and creating a trouble ticket. You complete the other troubleshooting steps after the trouble ticket has been prioritized.
14
Q
Which step of the troubleshooting model involves identifying whether hardware or software has been recently installed or reconfigured?
A. Identify symptoms
B. Establish a theory of probable cause
C. Establish a plan of action to resolve the problem and identify potential effects
D. Determine if anything has changed.
E. Test the theory to determine cause
F. Document findings, actions, and outcomes
A
D. Determine if anything has changed.
During the troubleshooting process, you must establish whether anything has changed. This typically involves asking the user whether any new or existing hardware or software has been installed or reconfigured.
15
Q
Which step of the troubleshooting model involves replacing components until a faulty hardware device is identified?
A. Duplicate the problem
B. Gather information
C. Test the theory to determine the cause
D. Establish a plan of action to resolve the problem
E. Verify full system functionality
F. Document findings, actions, and outcomes
A
C. Test the theory to determine the cause
After you have established a theory of probable cause, you can try to test the theory by replacing hardware components one by one until you find the faulty device.
16
Q
Ed is a first-tier support technician. He receives the help calls listed here. His job is to assign them priorities based on their severity. Which of the following should be the problem that receives the highest priority?
A. A problem with an order entry or customer service call center resource that affects an entire department, with multiple local area networks (LANs)
B. A fatal error that causes a single computer to fail
C. A problem with a mission-critical backbone router that affects an entire network
D. A problem with an application server that affects a single LAN
A
C. A problem with a mission-critical backbone router that affects an entire network
A problem that affects the entire network should be given highest priority. This includes a mission-critical backbone router. Problems that affect multiple LANs or an entire department are generally given the next highest priority. An application problem that affects a shared application server on a LAN should be given the next highest priority. A problem with a single user’s computer should be given the lowest priority if the other problems have been reported.
17
Q
Ed is a first-tier support technician. He receives the help calls listed here. His job is to assign them priorities based on their severity. Which of the following should be the problem that receives the lowest priority?
A. A problem with an order entry or customer service call center resource that affects an entire department, with multiple local area networks (LANs)
B. A fatal error that causes a single computer to fail
C. A problem with a mission-critical backbone router that affects an entire network
D. A problem with an application server that affects a single LAN
A
B. A fatal error that causes a single computer to fail
A problem that affects the entire network should be given highest priority. This includes a mission-critical backbone router. Problems that affect multiple LANs or an entire department are generally given the next highest priority. An application problem that affects a shared application server on a LAN should be given the next highest priority. A problem with a single user’s computer should be given the lowest priority if the other problems have been reported.
18
Q
When you troubleshoot a network problem, it is possible to introduce another problem while attempting to fix the original one. In which step of the troubleshooting process should you be aware of the residual effects that changes might have on the network?
A. Identify the problem
B. Establish a theory of probable cause
C. Test the theory to determine cause
D. Establish a plan of action to resolve the problem
E. Implement the solution or escalate as necessary
F. Verify full system functionality
G. Document findings, actions, and outcomes
A
D. Establish a plan of action to resolve the problem
After you identify a problem and establish and test a theory of its probable cause, you must create a plan of action to resolve the problem and identify any potential effects (positive or negative) your solution might have. Then, you implement your solution, test the results, and finish documenting the incident.
19
Q
In which troubleshooting step do you create a record of your activities and inform the user of what happened and why?
A. Identify the problem
B. Establish a theory of probable cause
C. Test the theory to determine cause
D. Establish a plan of action to resolve the problem and identify potential effects
E. Implement the solution or escalate as necessary
F. Verify full system functionality and, if applicable, implement preventive measures
G. Document findings, actions, and outcomes
A
G. Document findings, actions, and outcomes
The last step of the troubleshooting process is to document the solution and explain to the user what happened and why. In reality, documentation should begin when the problem is reported, and the documentation should be updated throughout the troubleshooting process.
20
Q
Which of the following Windows tools uses ICMP messages and manipulates IPv4 time-to-live values to illustrate the route packets take through an internetwork?
A. Ping
B. Netstat
C. Route
D. Tracert
E. Nslookup
A
D. Tracert
he Windows tracert tool transmits a series of ICMP messages with incrementing time-to-live (TTL) values, which identify each router on the path the packets take through the network. ping uses ICMP, but it does not manipulate TTLvalues.
21
Q
Users are having trouble connecting to Internet hosts. Alice suspects that there is a problem with the Domain Name System (DNS) server, and she wants to verify this. Which of the following steps can she take to determine whether the DNS server is resolving Internet hostnames?
A. Issue the ipconfig command from a local workstation
B. Try to connect to a host using the Internet Protocol (IP) address instead of the hostname
C. Ping the DNS server to see if it is functioning
D. Use the tracert command to test the functionality of the DNS server
A
B. Try to connect to a host using the Internet Protocol (IP) address instead of the hostname
If Alice suspects that a DNS server isn’t resolving hostnames, she should try connecting to a remote host using the IP address instead of the name. If she can connect, she knows that all internal local area network (LAN) components and the Internet gateway are functioning, and the remote host is functioning. The problem most likely lies within the DNS server itself. If Alice can’t connect to a remote host using the IP address, the problem isn’t the DNS server. She would need to do more testing to isolate the problem device and the affected area.
22
Q
Which of the following types of wiring faults cannot be detected by a wiremap tester?
A. Split pairs
B. Open circuits
C. Short circuits
D. Transposed wires
A
A. Split pairs
A wiremap tester consists of a main unit that connects to all eight wires of a UTP cable at once and a loopback device that you connect to the other end, enabling you to test all of the wires at once. A wiremap tester can detect opens and shorts, as well as transposed wires. However, it cannot detect split pairs because, in that fault, the pins are properly connected.
23
Q
After connecting a tone generator to the green wire at one end of a twisted pair cable run, Ralph proceeds to the other end of the cable and touches the locator to each of the eight pins in turn. The green wire and the green striped wire both produce a tone. What type of wiring fault has Ralph discovered?
A. Split pair
B. Far-end crosstalk
C. Transposed wires
D. Short circuit
E. Delay skew
A
D. Short circuit
The first and most essential test that installers must perform on every cable run is a continuity test, which ensures that each wire on both ends of the cable is connected to the correct pin and only the correct pin. If a pin on one end of a cable run is connected to two or more pins on the other end, you have a short circuit.
24
Q
Which of the following Windows command-line utilities produced the output shown here?
A. ping
B. tracert
C. netstat
D. arp
A
D. arp
Running the arp utility with the -a parameter on a Windows system displays the contents of the Address Resolution Protocol (ARP) cache. The cache contains records of the IP addresses on the network that arp has resolved into MAC addresses. The ping, tracert, and netstat utilities are not capable of producing this output.
25
Which of the following Windows command-line utilities produced the output shown here?
A. ping
B. tracert
C. netstat
D. arp
B. tracert
The Windows tracert utility functions by transmitting a series of Internet Control Message Protocol (ICMP) Echo Request messages to a specified destination with incrementing time-to-live (TTL) values. Each successive message reaches one hop farther on the route to the destination before timing out. The tracert display therefore lists the names and addresses of the routers packets must traverse to reach the destination. The ping, netstat, and arp utilities are not capable of producing this output.
26
Which of the following Windows command-line utilities produced the output shown here?
A. ping
B. tracert
C. netstat
D. arp
A. ping
The Windows ping utility functions by transmitting a series of Internet Control Message Protocol (ICMP) Echo Request messages to a specified destination. The destination system responds with ICMP Echo Reply messages that are listed in the output display. The tracert, netstat, and arp utilities are not capable of producing this output.
27
Which of the following Windows command-line utilities produced the output shown here?
A. ping
B. tracert
C. netstat
D. arp
C. netstat
Running the Windows netstat utility with no parameters generates a list of the workstation's active connections. The ping, tracert, and arp utilities are not capable of producing this output.
28
Which of the following command-line utilities is capable of performing the same basic function as traceroute or tracert?
A. ping
B. pathping
C. netstat
D. route
B. pathping
Like traceroute and tracert, pathping is capable of generating a list of the routers that packets pass through on the way to a specific destination system. pathping also displays the percentage of lost packets for each hop, which traceroute and tracert cannot do. The ping, netstat, and routeutilities are not capable of displaying route traces
29
What is the name for a device that determines the length of a cable by transmitting a signal at one end and measuring how long it takes for a reflection of the signal to return from the other end?
A. Fox and hound tester
B. Wiremap tester
C. Time domain reflectometer
D. Voltage event recorder
E. Butt set
C. Time domain reflectometer
The technique that provides this capability is called time domain reflectometry (TDR). The tester transmits a signal over the cable and measures how long it takes for a reflection of the signal to return from the other end. Using this information and the cable's nominal velocity of propagation (NVP)—a specification supplied by the cable manufacturer—the device can calculate the length of a cable run.
30
Which TCP/IP utility should you use to most easily identify a malfunctioning router on your network?
A. ifconfig
B. ping
C. traceroute
D. netstat
C. traceroute
The traceroute (or tracert) utility can locate a malfunctioning router by using an Echo Request messages with incrementing TTL values. ifconfig is a network configuration utility for Unix and Linux systems; ping can test connectivity to another TCP/IP system, but it cannot locate a malfunctioning router; and netstat displays information about network connections and traffic but cannot locate a malfunctioning router.
31
Which of the following protocols does the ping program never use to carry its messages?
A. Ethernet
B. ICMP
C. IP
D. UDP
E. TCP
E. TCP
All Windows ping transactions use ICMP messages. ICMP messages are encapsulated directly within IP datagrams; they do not use transport layer protocols, such as UDP. ping transactions to destinations on the local network are encapsulated within Ethernet frames. On Unix and Linux, ping uses UDP, which is also encapsulated in IP datagrams.
32
Which of the following commands displays the routing table on the local computer?
A. arp –r
B. netstat –r
C. ifconfig –r
D. telnet –r
B. netstat –r
The netstat utility can display the routing table, along with other types of network traffic and port information. The arp utility is for adding addresses to the ARP cache; it cannot display the routing table. The ifconfig command displays TCP/IP configuration information on Unix and Linux systems; it cannot display the routing table. Telnet is a terminal emulation program; it cannot display the routing table.
33
A routine test of a newlyinstalled twisted pair cable run with a wiremap tester indicates that there is a short circuit on one of the wires. Which of the following procedures might possibly correct the fault?
A. Use a different pinout on both ends of the cable
B. Replace the connectors at both ends of the cable run
C. Move the cable away from any potential sources of electromagnetic interference
D. Use a higher grade of UTP cable
B. Replace the connectors at both ends of the cable run
A short circuit is a wiring fault indicating that a pin at one end of a cable run is connected to two pins at the other end. To correct the problem, you must replace the connector with the faulty wiring. None of the other suggestions are solutions for a wiring fault.
34
Ralph is a new hire working on a network that uses Cat5 unshielded twisted pair cable, which was installed several years ago. Over time, some of the paper labels that the original cable installers used to identify the wall plates and patch panel connectors have worn away or fallen off. As a result, Ralph has quite a few cable runs that he is unable to identify. After checking with his supervisor, Ralph discovers that the company has no cable testing equipment and is unwilling to hire a consultant just to identify cable runs. What is the most inexpensive tool Ralph can use to associate unlabeled wall plates with the correct patch panel ports?
A. A wiremap tester
B. A cable certifier
C. A tone generator and locator
D. A time domain reflectometer
C. A tone generator and locator
All of the suggested tools are cable of associating wall plates with the correct patch panel ports, but the tone generator and locator is by far the most inexpensive solution.
35
Which of the following devices is an essential tool for technicians working on telephone cables but is not needed for data networking cable installations?
A. Tone generator and locator
B. Wiremap tester
C. Cable certifier
D. Butt set
D. Butt set
Telephone cable technicians have their own specialized tools, such as the butt set, a one-piece telephone handset with alligator clips that enables its operator to connect to a line anywhere that the cables are accessible.
36
Which of the following command lines will produce the output shown in the figure?
A. ping 10.0.0.1 -t
B. ping 10.0.0.1 -n 2048
C. ping 10.0.0.1 -l 2048 -n 11
D. ping 10.0.0.1 -l 2048 -t
E. ping 10.0.0.1 -n 2048 -t 11
C. ping 10.0.0.1 -l 2048 -n 11
Running ping with the -l parameter enables you to specify the size of the messages sent to the target, in this case, 2028 bytes. The -n parameter enables you to specify the number of messages the ping tool should transmit, in this case 11. Combining these two parameters generates the output in the figure. The -t parameter causes the ping tool to transmit messages until manually halted.
37
Which of the following parameters causes the ping tool to transmit messages continually until manually halted?
A. -n
B. -t
C. -i
D. -a
B. -t
Running the ping tool with the -t parameter causes it to send messages to the target continuously until you manually stop it. The -n parameter enables you to specify the number of messages the ping tool should transmit. The -i parameter enables you to specify the time-to-live (TTL) value of the messages ping transmits. The -a parameter resolves an IP address you specify as the target to a hostname.
38
Which of the following tools can you use to test the optical loss in a fiber-optic cable?
A. An OLTS
B. A TDR
C. A light meter
D. A wiremap tester
A. An OLTS
An optical loss test set (OLTS) identifies signal loss in fiber optic cabling. A time domain reflectometer (TDR) measures electrical signals in copper-based cabling, not light signals. A light meter measures the strength of light signals on fiber optic cable, but it cannot generate the signal needed to test optical loss. Wiremap testers are used only on copper cables, not fiber optic.
39
Which of the following commands enables you to view the ARP table stored in memory?
A. arp -c
B. arp -d
C. arp -a
D. arp -s
C. arp -a
The arp -a command displays the entries in the ARP table stored in its cache. The arp -dcommand is for deleting entries, and the arp -s command is for adding entries. The arp -ccommand is not a valid option.
40
Which of the following command-line utilities enables you to generate Domain Name System (DNS) request messages?
A. ifconfig
B. nslookup
C. nbtstat
D. netstat
B. nslookup
The nslookup tool enables you to generate DNS request messages from the command line and send them to a specific DNS server. The other options listed are not DNS utilities.
41
Which of the following troubleshooting tools can test cabling for length, attenuation, near end crosstalk (NEXT), equal level far end crosstalk (ELFEXT), propagation delay, delay skew, and return loss?
A. Wiremap tester
B. Cable certifier
C. Time domain reflectometer (TDR)
D. Optical loss test set (OLTS)
B. Cable certifier
You can use a cable certifier to identify a variety of cable performance characteristics, typically including cabling lengths, signal attenuation, crosstalk, propagation delay, delay skew, and return loss, in addition to providing all the functionality of a wiremap tester. The other tools listed are dedicated to a single testing modality and do not test for crosstalk.
42
Which of the following command-line utilities enables you to view the Internet Protocol (IP) configuration on a Unix or Linux host?
A. ifconfig
B. nslookup
C. ipconfig
D. netstat
A. ifconfig
On a Unix or Linux host, the ifconfig command displays the system's current IP configuration settings and parameters. ipconfig is a Windows command-line utility that performs the same basic function. The other options are command-line utilities that do not display IP configuration information.
43
Which of the following Windows commands enables you to delete the entire ARP cache?
A. arp -c \*
B. arp -d \*
C. arp -a
D. arp -s
B. arp -d \*
The arp -d command is for deleting cache entries, and by running it with the asterisk wildcard, the command deletes all of the entries in the cache. The arp -a command displays the entries in the ARP table stored in its cache, and the arp -s command is for adding entries. The arp -c \* command is not a valid option.
44
Which of the following troubleshooting tools is not used to test copper cabling installations?
A. Wiremap tester
B. Multimeter
C. Tone generator and locator
D. OTDR
D. OTDR
An optical time domain reflectometer (OTDR) is a device that transmits light pulses over a fiber-optic network and measures the time interval and strength of the returning pulse, to measure the length of the cable run. An OTDR can be used to locate fiber-optic cable breaks, as well as characterize a cable run's reflectance, optical return loss, and other characteristics. Multimeters, tone generators, and wiremap testers are all devices that work only with copper networks.
45
Ralph has been advised to check his Linux web servers for open ports that attackers might be able to use to penetrate the servers’ security. Which of the following utilities can Ralph use to do this?
A. tcpdump
B. dig
C. iptables
D. nmap
D. nmap
The nmap utility is capable of scanning a system for open ports that might be a security hazard. The tcpdump, dig, and iptables utilities cannot do this.
46
Which of the following parameters enables you to specify the time-to-live (TTL) value of the messages ping transmits?
A. -n
B. -t
C. -i
D. -a
C. -i
Running the ping tool with the -i parameter enables you to specify the time-to-live (TTL) value of the messages ping transmits. The -t parameter causes the ping tool to send messages to the target continuously until you manually stop it. The -n parameter enables you to specify the number of messages the ping tool should transmit. The -a parameter resolves an IP address you specify as the target to a hostname.
47
Ralph is the network administrator of his company's network. He has had three users call the help desk to report that they are having problems connecting to the local application server. Comparing their stories, Ralph suspects that their Transmission Control Protocol (TCP) connections are being dropped. The users are not having problems connecting to any other hosts on the network. To troubleshoot this problem, Ralph decides to use a protocol analyzer. He wants to store and view only the traffic relating to the hosts and server that are having problems. How can Ralph do this?
A. Configure a display filter.
B. Configure a capture filter.
C. Set a trap on the analyzer.
D. Configure both a capture and a display filter.
B. Configure a capture filter.
Ralph wants to store and view only the traffic relating to the hosts that are experiencing problems. The best way to do this is to set a capture filter. Capture filters determine what is stored in the buffer. Display filters only determine what is displayed from the contents of the buffer. You do not set a trap on an analyzer—you set traps on Simple Network Management Protocol (SNMP) agents. Also, there is no need to configure both a capture filter and a display filter. If you set a capture filter that blocks all other traffic from entering the buffer, the display filter would be redundant.
48
Ralph is a new hire for a consulting firm that frequently performs cable installations. He is trying to learn more about the tools needed to install internal cable runs. To that end, which of the following statements about cable crimpers has Ralph found to be true?
A. Cable installers use a crimper to attach keystone connectors to lengths of bulk cable.
B. Cable installers use a crimper to attach RJ45 connectors to lengths of bulk cable.
C. You need to purchase a separate crimper for each type of cable to which you want to attach connectors.
D. Making your own patch cables by applying connectors yourself is always more economical than buying prefabricated patch cables.
B. Cable installers use a crimper to attach RJ45 connectors to lengths of bulk cable.
A crimper is a plier-like device that cable installers use to create patch cables by attaching RJ45 connectors to lengths of bulk cable.
49
Which of the following troubleshooting tools enables you to copy all of the packets transmitted over a network to a buffer, interpret the protocols used in the packets, and display the output?
A. Event Viewer
B. Traffic monitor
C. Protocol analyzer
D. Management console
C. Protocol analyzer
A protocol analyzer copies all network traffic, interprets the protocol headers and fields, and displays the output. The Event Viewer displays system, application, and security event logs on a single computer. There is no network troubleshooting tool called a traffic monitor. A management console is a remote monitoring and management device that queries Simple Network Management Protocol (SNMP) agents.
50
Which of the following are tools that run only on Unix or Linux systems?
A. tcpdump
B. dig
C. iptables
D. ifconfig
E. route
E. route
Of the utilities listed, tcpdump, dig, iptables, and ifconfig are all tools that run on Unix/Linux systems only. The route utility runs on both Unix/Linux and Windows.
51
Which of the following Windows command-line utilities produced the output shown here?
A. nslookup
B. pathping
C. netstat
D. route
A. nslookup
nslookup is a command-line utility that generates DNS resource record requests and sends them to a specific DNS server. The output shown here specifies first the name and address of the DNS server to which the request was sent and then the response to the request, containing the name to be resolved and the IP addresses contained in the server's resource record for that name. The pathping, netstat, and route utilities cannot perform DNS queries.
52
Which of the following parameters enables you to specify the number of messages the pingtool transmits?
A. -n
B. -t
C. -i
D. -a
A. -n
Running the ping tool with the -n parameter enables you to specify the number of messages the ping tool should transmit with each execution. The -t parameter causes the ping tool to send messages to the target continuously until you manually stop it. The -i parameter enables you to specify the time-to-live (TTL) value of the messages ping transmits. The -aparameter resolves an IP address you specify as the target to a hostname.
53
Which of the following cable testing tools are used only on fiber-optic networks?
A. OTDR
B. Multimeter
C. Tone generator
D. Punchdown tool
A. OTDR
An optical time domain reflectometer (OTDR) is a device that transmits light pulses over a fiber-optic network and measures the time interval and strength of the returning pulse, to measure the length of the cable run. An OTDR can be used to locate fiber-optic cable breaks, as well as characterize a cable run's reflectance, optical return loss, and other characteristics. Multimeters, tone generators, and punchdown tools are all devices that work only with copper networks.
54
Which of the following command-line utilities can only run on Unix and Linux systems?
A. ping
B. ipconfig
C. tracert
D. ifconfig
E. netstat
D. ifconfig
The ifconfig command runs only on Unix and Linux systems. The ping and netstatutilities run on both Windows and Unix/Linux systems. The ipconfig and tracertcommands run only on Windows, although there is a Unix/Linux version of tracert called traceroute.
55
Which of the following command-line utilities can only run on Windows systems?
A. ping
B. ipconfig
C. traceroute
D. ifconfig
E. netstat
B. ipconfig
The ipconfig command runs only on Windows, although there is a similar Unix/Linux-only command called ifconfig. The ping and netstat utilities run on both Windows and Unix/Linux systems. The traceroute utility runs only on Unix/Linux systems, although there is a Windows version called tracert.
56
Which of the following netstat commands can tell you how many IPv6 packets have been received on a particular Windows workstation?
A. netstat -a
B. netstat -s
C. netstat -e
D. netstat -r
B. netstat -s
The netstat -s command displays packet counts and other traffic statistics for the IPv6, IPv4, ICMP, TCP, and UDP protocols. The netstat -a command displays all of a workstation's current connections and ports on which it is listening. The netstat -ecommand displays Ethernet statistics, such as the number of bytes and packets sent and received. The netstat -r command displays the computer's routing table.
57
Which of the following commands can Ralph use to display the number of bytes that a Windows workstation has transmitted?
A. netstat
B. tcpdump
C. ipconfig
D. iptables
A. netstat
Running netstat with the -e parameter on a Windows workstation displays Ethernet statistics, including the number of bytes and packets the workstation has sent and received. The ipconfig command displays TCP/IP configuration data; it does not display network traffic statistics. The tcpdump and iptables commands both run only on Unix and Linux workstations.
58
Alice is troubleshooting a Windows server, and while doing so she runs the following command: ping 127.0.0.1. The command completes successfully. What has Alice proven by doing this?
A. That the computer's network adapter is functioning properly
B. That the computer's TCP/IP networking stack is loaded and functioning
C. That the computer's IP address is correct for the network
D. Nothing at all
B. That the computer's TCP/IP networking stack is loaded and functioning
The IP address 127.0.0.1 is a dedicated loopback address that directs outgoing IP traffic directly into the incoming IP traffic buffer. A successful ping test using that address indicates that the computer's TCP/IP stack is functioning properly, but the traffic never reaches the network adapter or the network, so the test does not confirm that the adapter is functioning or that the computer has a correct IP address for the network.
59
Ralph is the administrator of his company's network. He has a Dynamic Host Configuration Protocol (DHCP) server configured to supply Internet Protocol (IP) addresses and configuration information to all of the Windows computers on the network. One of the Windows users reports that she cannot connect to the network. Which of the following commands can Ralph run on her computer to verify the status of the computer's IP settings and configuration parameters?
A. ifconfig
B. ipconfig
C. msinfo32
D. tracert
B. ipconfig
ipconfig is a Windows command that displays a computer's current IP address and TCP/IP configuration settings, including whether the computer has obtained its address from a DHCP server.
60
Which of the following cable installation tools is likely to be the most expensive?
A. A crimper
B. A cable certifier
C. A punchdown tool
D. A wiremap tester
B. A cable certifier
Crimpers and punchdown tools are relatively simple and inexpensive mechanical devices that cable installers use to connect bulk cable to connectors. A wiremap tester is an electronic device for cable testing, but it is still relatively simple. A cable certifier is a complex electronic device that can perform a battery of tests on a cable run, confirm that the cable conforms to the required wiring standards, and maintains records of the testing procedure. Cable certifiers are by far the most expensive of the devices listed.
61
\Which of the following route commands displays the contents of a Windows computer's IPv6 routing table only?
A. route print
B. route print -6
C. route list -6
D. route list
B. route print -6
The route print command displays both the IPv4 and IPv6 routing tables. To display only the IPv6 routing table, you add the -6 parameter to the route print command. route list and route list -6 are not valid commands.
62
What is the function of the tool shown in the following figure?
A. By placing the tool at one end of a wire, it generates a tone that can be detected at the other end.
B. To connect a bulk cable to a keystone connector, you use the tool to punch each wire down into the correct receptacle on the connector.
C. By touching the end of the tool to a copper cable, you can detect and measure the electrical current flowing through it.
D. By connecting the tool to the end of a fiber-optic cable, you can measure the length of the cable run.
C. By touching the end of the tool to a copper cable, you can detect and measure the electrical current flowing through it.
The device shown in the figure is a multimeter, which is used to measure the electric current on a copper conductor, such as an unshielded twisted pair network. This tool is not capable of performing any of the tasks described in the other options.
63
What is the function of the tool shown in the following figure?
A. When you place the tool at one end of a wire, it generates a tone that can be detected at the other end.
B. To connect a bulk cable to a keystone connector, you use the tool to punch each wire down into the correct receptacle on the connector.
C. By touching the end of the tool to a copper cable, you can detect and measure the electrical current flowing through it.
D. By connecting the tool to the end of a fiber-optic cable, you can measure the length of the cable run.
B. To connect a bulk cable to a keystone connector, you use the tool to punch each wire down into the correct receptacle on the connector.
The device shown in the figure is a punchdown tool, used to connect unshielded twisted pair cable ends to the keystone connectors used in modular wall plates and patch panels. After lining up the individual wires in the cable with the connector, you use the tool to press each wire into its slot. The tool also cuts the wire sheath to make an electrical contact and trims the end of the wire. This tool is not capable of performing any of the tasks described in the other options.
64
What is the function of the tool shown in the following figure?
A. When you place the tool at one end of a wire, it generates a tone that can be detected at the other end.
B. To connect a bulk cable to a keystone connector, you use the tool to punch each wire down into the correct receptacle on the connector.
C. By touching the end of the tool to a copper cable, you can detect and measure the electrical current flowing through it.
D. By connecting the tool to the end of a fiber-optic cable, you can measure the length of the cable run.
A. When you place the tool at one end of a wire, it generates a tone that can be detected at the other end.
The device shown in the figure is a tone generator and locator, used to test unshielded twisted pair wiring and detect certain basic wiring faults. This tool is not capable of performing any of the tasks described in the other options.
65
What is the function of the tool shown in the following figure?
A. When you placethe tool at one end of a wire, it generates a tone that can be detected at the other end.
B. To attach a bulk cable end to an RJ45 connector, you use the tool to squeeze the connector closed, forcing the wire ends to contact the connector's pins.
C. By touching the end of the tool to a copper cable, you can detect and measure the electrical current flowing through it.
D. By connecting the clips to pins in a punchdown block, you can access telephone circuits in order to test them or place telephone calls.
D. By connecting the clips to pins in a punchdown block, you can access telephone circuits in order to test them or place telephone calls.
The device shown in the figure is a butt set, a basic tool of telephone installers and linesworkers. This tool is not capable of performing any of the tasks described in the other options.
66
What is the function of the tool shown in the following figure?
A. When you placethe tool at one end of a wire, it generates a tone that can be detected at the other end.
B. To attach a bulk cable end to an RJ45 connector, you use the tool to squeeze the connector closed, forcing the wire ends to contact the connector's pins.
C. By touching the end of the tool to a copper cable, you can detect and measure the electrical current flowing through it.
D. By connecting the clips to pins in a punchdown block, you can access telephone circuits in order to test them or place telephone calls.
B. To attach a bulk cable end to an RJ45 connector, you use the tool to squeeze the connector closed, forcing the wire ends to contact the connector's pins.
The device shown in the figure is a crimper, which is used to create patch cables by attaching connectors to both ends of a relatively short length of bulk cable. This tool is not capable of performing any of the tasks described in the other options.
67
What is the name of the tool shown in the following figure?
A. Butt set
B. Crimper
C. Tone generator and locator
D. Punchdown tool
B. Crimper
The device shown in the figure is a crimper, which is used to create patch cables by attaching RJ45 connectors to both ends of a relatively short length of bulk cable. You use the tool to squeeze the connector closed, forcing the wire ends to contact the connector's pins.
68
What is the name of the tool shown in the following figure?
A. Butt set
B. Crimper
C. Tone generator and locator
D. Punchdown tool
A. Butt set
The device shown in the figure is a butt set, a basic tool of telephone installers and linesworkers. By connecting the clips to pins in a punchdown block, you can access telephone circuits in order to test them or place telephone calls.
69
What is the name of the tool shown in the following figure?
A. Butt set
B. Crimper
C. Tone generator and locator
D. Punchdown tool
D. Punchdown tool
The device shown in the figure is a punchdown tool, used to connect unshielded twisted pair cable ends to the keystone connectors used in modular wall plates and patch panels. After lining up the individual wires in the cable with the connector, you use the tool to press each wire into its slot. The tool also cuts the wire sheath to make an electrical contact and trims the end of the wire.
70
What is the name of the tool shown in the following figure?
A. Multimeter
B. Butt set
C. Tone generator and locator
D. Punchdown tool
C. Tone generator and locator
The device shown in the figure is a tone generator and locator, used to test unshielded twisted pair wiring and detect certain basic wiring faults. When you place the tool at one end of a wire, it generates a tone that can be detected at the other end.
71
What is the name of the tool shown in the following figure?
A. Multimeter
B. Butt set
C. Tone generator and locator
D. Punchdown tool
A. Multimeter
The device shown in the figure is a multimeter, a versatile device used to measure electrical current on copper cable connections. Multimeters are available with a wide range of features at a wide range of costs.
72
Ed is working the help desk at a local computer store, and he receives a call from a customer trying to set up a home network using Windows 10 and wired Ethernet equipment. The customer reports that, from her computer, she can see the two other computers in the house, but she cannot access the Internet. Ed asks her to run the ipconfig /all command and read the results to him. She says that her IP address is 172.16.41.2, her subnet mask is 255.255.255.0, and her default gateway is 172.16.43.1. Which of the following is most likely the cause of the customer's problem?
A. The customer's network cable is unplugged.
B. The customer has an incorrect subnet mask.
C. The customer has an incorrect default gateway address.
D. The computer's DNS record contains the wrong information.
C. The customer has an incorrect default gateway address.
Because the customer can access the other two computers in the house, Ed knows that her IP address and subnet mask are properly configured that the network cable is plugged in and functional. Ed also knows that the computer's DNS record does not play a role in outgoing connections. The problem is most likely the default gateway because the gateway address the customer specified is on another network, 172.16.43.0, rather than on her own network, 172.16.41.0.
73
Alice is attempting to troubleshoot a communication problem between two hosts on the same network. She decides to use a protocol analyzer to capture traffic on the network. After finishing the capture, Alice notices that there are over 15,000 frames in the protocol analyzer's capture buffer. She is having a difficult time identifying the frames that relate to the problem because there are so many in the buffer. She wants to eliminate the extraneous frames from her view, enabling her to view only the frames transmitted by these two hosts. What does Alice have to do to accomplish this?
A. Configure a display filter.
B. Configure a capture filter.
C. Delete the extraneous frames from the buffer.
D. Configure a capture and display filter.
A. Configure a display filter.
Once the frames are in the buffer, Alice can configure a display filter to block the unwanted frames from view. This does not delete them from the buffer. Since the capture was already performed, there is no need to restart the capture. Configuring a capture filter will not meet the requirements, because the filter will eliminate the other frames completely from the buffer. It is not possible to delete frames from an analyzer buffer.
74
Ed is working the help desk at a local computer store, and he receives a call from a customer trying to set up a home network using Windows 10 and wired Ethernet equipment. The customer reports that she cannot access the other two computers in the house, nor can she access the Internet. Ed asks her to run the ipconfig /all command and read the results to him. She says that her IP address is 192.168.0.2, her subnet mask is 255.255.255.0, and her default gateway is 192.168.0.1. Which of the following is most likely the cause of the customer's problem?
A. The customer's network cable is unplugged.
B. The customer's network address cannot include a zero.
C. The customer has an incorrect subnet mask.
D. The customer has an incorrect default gateway address.
A. The customer's network cable is unplugged.
The customer's IP address, subnet mask, and default gateway are appropriate for her home network. There is nothing wrong with having a zero in the network address. Therefore, of the options presented, the only logical choice is that the network cable is unplugged.
75
Ralph is testing a twisted pair cable run using a tone generator and locator. When he applies the tone generator to one particular wire at one end of the cable, he fails to detect a tone at the other end. Which of the following faults has Ralph discovered?
A. Open
B. Short
C. Split pair
D. Crosstalk
A. Open
The failure to detect a tone on a wire indicates that there is either a break in the wire somewhere inside the cable or a bad connection with the pin in one or both connectors. This condition is called an open circuit. A short is when a wire is connected to two or more pins at one end of the cable. A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Crosstalk is a type of interference caused by signals on one wire bleeding over to other wires.
76
Ralph is testing a twisted pair cable run using a tone generator and locator. When he applies the tone generator to a particular pin at one end of the cable, he detects a tone on two pins at the other end. Which of the following faults has Ralph discovered?
A. Open
B. Short
C. Split pair
D. Crosstalk
B. Short
A short is when a wire is connected to two or more pins at one end of the cable or when the conductors of two or more wires are touching inside the cable. This would cause a tone applied to a single pin at one end to be heard on multiple pins at the other end. An open circuit would manifest as a failure to detect a tone on a wire, indicating that there is either a break in the wire somewhere inside the cable or a bad connection with the pin in one or both connectors. A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Crosstalk is a type of interference caused by signals on one wire bleeding over to other wires.
77
Ralph is using a tone generator and locator to test some newly installed twisted pair cable runs on his network. Which of the following cable faults will he be unable to detect?
A. Open
B. Short
C. Split pair
D. Transposed pairs
C. Split pair
A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Each pin on one end of the cable is correctly wired to the corresponding pin at the other end, but the wires inside the cable used to make the connections are incorrect. In a properly wired connection, each twisted pair should contain a signal and a ground wire. In a split pair, you can have two signal wires twisted together as a pair. This can generate excessive amounts of crosstalk, corrupting both of the signals involved. Because all of the pins are connected properly, a tone generator and locator cannot detect this fault.
78
Alice has been told by a consultant that the newly installed twisted pair cable runs on her network might have split pairs. Which of the following cable testing tools can she use to detect split pairs?
A. Tone generator and locator
B. Wiremap tester
C. Multimeter
D. Cable certifier
D. Cable certifier
A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Each pin on one end of the cable is correctly wired to the corresponding pin at the other end, but the wires inside the cable used to make the connections are incorrect. In a properly wired connection, each twisted pair should contain a signal and a ground wire. In a split pair, you can have two signal wires twisted together as a pair. This can generate excessive amounts of crosstalk, corrupting both of the signals involved. Because all of the pins are connected properly, a tone generator and locator cannot detect this fault, and neither can a wiremap tester or a multimeter. However, a cable certifier is a highly sophisticated electronic device that can detect all types of cable faults, including split pairs, as well as measure cable performance characteristics.
79
Which of the following terms describes a connectivity problem on wired networks that is caused by individual packets that are delayed due to network congestion, different routing, or queuing problems?
A. Latency
B. Attenuation
C. Jitter
D. Bottleneck
C. Jitter
When individual packets in a data stream are delayed, the resulting connectivity problem is called jitter. Although this condition might not cause problems for asynchronous applications, real-time communications, such as Voice over IP or streaming video, can suffer interruptions, from which the phenomenon gets its name. Latency describes a generalized delay in network transmissions, not individual packet delays. Attenuation is the weakening of a signal as it travels through a network medium. A bottleneck is a condition in which all traffic is delayed, due to a faulty or inadequate component.
80
Alice's company has moved to a building that was prewired for Ethernet. However, since installing the company's Gigabit Ethernet equipment using the existing cable runs, performance has been poor. After performing some packet captures and analyzing the traffic samples, Alice discovers that there are a great many Ethernet frames being retransmitted. Next, she examines the cable runs in the drop ceilings. They do not appear to be overly long, and they do not appear to run near any major sources of electromagnetic interference. Which of the following could be the problem?
A. Some of the cable runs are using T568A pinouts, and some are using T568B.
B. The only cables have two wire pairs connected, instead of four.
C. The existing cable is not rated for use with Gigabit Ethernet.
D. There are mismatched transceivers at the cable ends.
C. The existing cable is not rated for use with Gigabit Ethernet.
Of the options provided, the only possible source of the problem is that the cable runs are using a cable type not rated for Gigabit Ethernet. Some older buildings might still have Category 3 cable installed, which was used in the original twisted pair Ethernet specification. Cat3 is unsuitable for use with Gigabit Ethernet in many ways and can result in the poor performance that Alice is experiencing. A cable installation with runs wired using different pinout standards will not affect performance as long as each run uses the same pinouts at both ends. Gigabit Ethernet will not function at all if only two wire pairs are connected. The transceivers are located in the equipment that Alice company brought from the old location, so they are not mismatched.
81
Ralph is responsible for the network installation in a new building purchased by his company, and he has elected to have Category 6 unshielded twisted pair cable installed. The company president has asked him if it is possible to run their Gigabit Ethernet network using two of the wire pairs in the cable, while using the other two pairs for telephone connections. Ralph is not sure, so he sets up a lab network using cables with only two pairs connected. When he plugs computers into the switch and turns them on, the LEDs labeled 1000 light up, indicating that a Gigabit Ethernet connection has been established. Ralph gets excited at the thought of how much money he might save the company by using the same cable for both telephone and data. However, while the LED is lit, he can't seem to connect to another system over his test network. Which of the following describes what he must do to correct the problem?
A. Ralph must manually configure the network adapters to use Gigabit Ethernet, rather than let them auto negotiate.
B. Ralph is using the wrong two wire pairs for the Gigabit Ethernet connection. He must rewire the connectors.
C. Ralph is using the wrong pinout standard on his lab network. He must use T568A.
D. Ralph must use all four wire pairs for a Gigabit Ethernet connection.
D. Ralph must use all four wire pairs for a Gigabit Ethernet connection.
The auto negotiation mechanism is not the problem, nor is the pinout standard or Ralph's wire pair selection. The speed auto negotiation mechanism in Gigabit Ethernet uses only two wire pairs, so although the LEDs do light up successfully, a functional Gigabit Ethernet data connection requires all four wire pairs.
82
Ed is inspecting the cable runs recently installed for some new Gigabit Ethernet systems on his network. Looking at the patch panel connections, he notices that they are wired using the T568B pinout standard. However, when he examines the wall plate connections, he sees that they are wired using the T568A standard. What is the best way for Ed to resolve the problem?
A. Call the contractor and have all of the wall plate connectors rewired using the T568B standard.
B. Purchase crossover patch cables for all of the connections between the patch panel and the switches.
C. Configure the switches not to use a crossover circuit for all of the ports connected to the patch panel.
D. Do nothing. The cable runs will function properly as is.
D. Do nothing. The cable runs will function properly as is.
Cable runs are traditionally wired “straight through,” that is, with the transmit pins at one end wired to the transmit pins at the other end. It is the switch that is supposed to implement the crossover circuit that connects the transmit pins to the receive pins. Cable runs wired using T568A at one end and T568B at the other end create a crossover circuit in the cable run. At one time, this would have been a serious problem, but today's switches automatically configure crossover circuits as needed, so they will adjust themselves to adapt to the cable runs. All of the other options would correct the problem, but doing nothing is certainly the best option.
83
Alice has recently installed some new computers onto her Gigabit Ethernet network. To ensure best possible network performance, she has configured the network adapters in the new computers to run at 1 Gbps speed and use full-duplex communication. Once the computers are in service, however, Alice begins getting reports of extremely poor network performance on those machines. She tries running some ping tests and does not see any problem. She calls in a consultant to perform a packet analysis and the consultant detects large numbers of packet collisions, late collisions, cyclical redundancy check (CRC) errors, and runt frames. Which of the following could be the problem?
A. Duplex mismatch
B. TX/RX reversal
C. Incorrect cable type
D. Damaged cables
A. Duplex mismatch
There should be no collisions at all on a full-duplex network, so the problem is clearly related to the duplexing of the communications. Ethernet running over twisted pair cable, in its original half-duplex mode, detects collisions by looking for data on the transmit and receive pins at the same time. In full-duplex mode, data is supposed to be transmitted and received at the same time. When one side of a connection is configured to use full duplex, as Alice's new computers are, and the other end is configured to use half duplex (as the switches must be), the full-duplex communications on the one side look like collisions to the half-duplex side.
84
Ralph has two computers that he long ago networked together by plugging one end of an Ethernet cable into each machine. He recently bought an old Ethernet hub at a garage sale and wants to use it to expand his network. The hub has four numbered ports and a fifth port marked with an X. Ralph plugs one computer into port 1 using his existing cable and buys a new cable to plug the other computer into port 4. The two computers cannot communicate, however. Which of the following solutions will not enable his computers to communicate?
A. Move the port 4 cable to port 2.
B. Replace the old cable with a second new one.
C. Plug the computer with the old cable into the X port.
D. Plug the computer with the new cable into the X port.
A. Move the port 4 cable to port 2.
The problem is unlikely to be a bad hub port or a bad cable, so moving the cable from port 4 to port 2 will not help. The problem is the crossover circuit between the two computers. The two systems were once connected directly together, which means that Ralph was using a crossover cable. The hub also provides a crossover circuit (except in the X port), and old hubs often do not auto negotiate crossovers. Therefore, the connection has two crossovers, which is the equivalent of wiring transmit pins to transmit pins, instead of transmit pins to receive pins. All of the other options eliminate one of the crossover circuits, enabling the computers to be wired correctly.
85
Ed has discovered that some of the twisted pair cable runs on his newly installed Ethernet network are well over 100 meters long. Which of the following problems is his network likely to experience due to cable segments that are greater than the specified length?
A. Jitter
B. Attenuation
C. Crosstalk
D. EMI
B. Attenuation
Attenuation is the weakening of a signal as it travels long distances, whether on a wired or wireless medium. The longer the transmission distance, the more the signal weakens. Cable length specifications are designed in part to prevent signals from attenuating to the point at which they are unviable.
86
Ralph recently bought an old Ethernet hub and some twisted pair cables at a garage sale and wants to use them to build a home network. He plugs two computers into the hub using the cables but finds that the computers are unable to communicate. Then he notices that one of the ports in the hub is labeled with an X. He tries plugging one of the computers into the X port, and now they can communicate. Which of the following statements is the most likely explanation for this behavior?
A. The hub has a bad port.
B. One of the cables is a crossover cable.
C. Both of the cables are crossover cables.
D. The X port provides extra strength to the signals.
B. One of the cables is a crossover cable.
Older Ethernet hubs do not auto negotiate crossovers. Instead, they have an X (or uplink) port that provides a connection without a crossover circuit, so you can connect one hub to another. If both of the cables had been standard straight-through Ethernet cables or if both had been crossover cables, then plugging them into two regular ports should have worked. Because plugging one cable into the X port worked, this means that only one of the cables must be a crossover cable. The problem, therefore, was the cable, not the port. The X port does not provide extra strength to the signals.
87
Ed has discovered that some of the twisted pair cables on his newly installed network are running right alongside fluorescent light fixtures in the drop ceiling. Which of the following problems is the network likely to experience due to the cables’ proximity to the fixtures?
A. Jitter
B. Attenuation
C. Crosstalk
D. EMI
D. EMI
Fluorescent light fixtures and other devices in an office environment can generate magnetic fields, resulting in electromagnetic interference (EMI). When a copper-based cable runs too near to such a device, the magnetic fields can generate an electric current on the cable that interferes with the signals exchanged by network devices. Jitter, crosstalk, and attenuation are all conditions that can affect the performance of a wired network, but they are not directly related to the cables’ proximity to light fixtures.
88
Alice is a consultant who has been hired to move a client's old 20-node coaxial Ethernet network to a new location. She disassembles all of the network cabling and other components and packs them for shipping. At the new site, she sets up all of the computers, plugs a T-connector into each network adapter, and connects the cables, running them from one computer to the next to form the bus. When Alice is finished, she starts the computers and tests their network connectivity. She finds that 12consecutive computers can communicate with each other, and the other 8can communicate with each other, but the 12cannot communicate with the 8. She makes sure that all of the connectors are securely tightened, especially the ones on the12th computer, but the problem persists. Which of the following is the most likely cause of the difficulty?
A. Alice has forgotten to terminate the computers at each end of the bus.
B. One of the connectors on the 12th computer has a bent pin.
C. Alice has forgotten to ground the network.
D. The transmit and receive pins are reversed on the 12th computer.
B. One of the connectors on the 12th computer has a bent pin.
A bent pin on one of the twelfth computer's connections would cause a break in the bus, essentially forming two networks that operate independently. The failure to terminate or ground the network would not produce this type of fault. Reversing the transmit and receive pins is not possible on a coaxial connection, due to the architecture of the cable.
89
Which of the following types of interference on a twisted pair network are designed to be prevented by the twists in the wire pairs inside the cable?
A. Crosstalk
B. EMI
C. Attenuation
D. Latency
A. Crosstalk
Crosstalk is a type of interference that occurs on copper-based networks when in a signal transmitted on one conductor bleeds over onto another nearby conductor. Twisted pair cables, which have eight or more conductors compressed together inside one sheath, are particularly susceptible to crosstalk. Twisting each of the separate wire pairs tends to reduce the amount of crosstalk to manageable levels. Twisting the wire pairs does not prevent signals from being affected by electromagnetic interference (EMI) or attenuation. Latency is a measurement of the time it takes for a signal to travel from its source to its destination.
90
Which of the following indicators can you use to determine whether an adapter is connected to a functioning hub or switch?
A. Speed light-emitting diode (LED)
B. Collision LED
C. Link pulse LED
D. Status LED
C. Link pulse LED
The link pulse LED indicates the adapter is connected to a functioning hub or switch. The speed LED specifies the data rate of the link. The collision LED lights up when collisions occur. There is no status LED on a network interface adapter.
91
Ralph has been asked to create some new patch cables that will be used to connect patch panel ports to the network switches. He has been told that the patch panel connectors are all wired using the T568A pinout standard. Which of the following instructions should Ralph use when creating the patch cables?
A. Use T568A at both ends
B. Use T567B at both ends
C. Use T568A at one end and T568B at the other end
D. Use either standard, as long as both ends are the same
D. Use either standard, as long as both ends are the same
Either the T568A or the T568B pinout standard is acceptable. The patch cables will function properly as long as both ends are wired using the same pinout standard.
92
Ed has discovered that, on some of his newly installed twisted pair cable runs, the installer has stripped away nearly a foot of the cable sheath at each end and has untwisted the wire pairs before attaching them to the connectors. Which of the following problems is the network more likely to experience due to the untwisted wires?
A. Jitter
B. Attenuation
C. Crosstalk
D. EMI
C. Crosstalk
Crosstalk is a type of interference that occurs on copper-based networks when in a signal transmitted on one conductor bleeds over onto another nearby conductor. Twisted pair cables, which have eight or more conductors compressed together inside one sheath, are particularly susceptible to crosstalk. Twisting each of the separate wire pairs tends to reduce the amount of crosstalk to manageable levels. Untwisting the pairs leaves them more susceptible to crosstalk.
93
Ed is experiencing bad network performance on some new twisted pair cable runs that he recently had installed. After ruling out all other causes, he tests the cables with a tone generator and locator and finds no faults. Finally, he examines the cable connectors more closely and finds that, while the pins at one end of the cable are correctly connected to their corresponding pins at the other end, in some cases there are two solid color wires twisted together in a pair. Which of the following types of faults has Ed discovered?
A. Open circuit
B. Short circuit
C. Split pairs
D. Transposed wires
C. Split pairs
A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Each pin on one end of the cable is correctly wired to the corresponding pin at the other end, but the wires inside the cable used to make the connections are incorrect. In a properly wired connection, each twisted pair should contain a colored signal wire and a striped ground wire. In a split pair, you can have two signal wires twisted together as a pair. This can generate excessive amounts of crosstalk, corrupting both of the signals involved. Because all of the pins are connected properly, a tone generator and locator cannot detect this fault.
94
Ralph has been asked to create some new patch cables that will be used to connect patch panel ports to the network switches. He has been told to use the T568B pinout standard for all of the cable connectors. Ralph gathers the materials and the tools needed to complete the task, but he is not sure about the T568B pinout. Which of the following pinouts must Ralph use when creating the patch cables?
A. White/orange, orange, white/green, blue, white/blue, green, white/brown, brown
B. White/green, green, white/orange, blue, white/blue, orange, white/brown, brown
C. White/orange, orange, white/green, green, white/blue, blue, white/brown, brown
D. White/brown, white/green, white/orange, blue, white/blue, orange, green, brown
A. White/orange, orange, white/green, blue, white/blue, green, white/brown, brown
Option A is the T568B pinout that Ralph should use when attaching connectors to the cables. Option B is the T568A pinout, which would also work but that Ralph has been instructed not to use. Options C and D are both incorrect and can result in excessive amounts of crosstalk.
95
Ralph is adding new workstations to his wireless network, which uses an access point that is configured to use WPA2 encryption. However, after configuring the wireless network adapter on the first workstation, Ralph finds that it is not connecting to the network. The access point is listed on the Available Networks display, and there are no error messages or indications of a problem, just a failure to connect. Which of the following is most likely to be the problem?
A. Incorrect passphrase
B. Channel overlap
C. Incorrect SSID
D. Poor signal-to-noise ratio
A. Incorrect passphrase
Specifying the wrong passphrase for the encryption protocol is the most common cause of a failure to connect to the network with no indication of an error. Channel overlap or a poor signal-to-noise ratio, caused by a microwave oven or other device, could result in a weak signal, either of which would be indicated in the list of available networks. Incorrect SSID is not likely to be the error, as long as Ralph selected the access point from the list.
96
Ralph is the administrator of a small company's wireless network. He has recently discovered evidence that users outside of the company's office space have been accessing its wireless network. The office is located in a narrow space against the building's outside wall. Ralph is concerned that the network's wireless access point is extending coverage outside the building. Speaking with a consultant friend of his, Ralph is advised to install a different type of antenna on his access point. Which of the following antenna types would most likely help Ralph to alleviate the problem?
A. Dipole
B. Yagi
C. Patch
D. Unidirectional
C. Patch
A patch antenna is a flat device that transmits signals in a half-spherical pattern. By placing the antenna against the building's outer wall, Ralph can provide coverage inside the building and minimize coverage extending to the outside. A dipole antenna is another name for the omnidirectional antenna usually provided with an access point. A unidirectional antenna directs signals in a straight line, which would not provide the coverage Ralph needs. A Yagi antenna is a type of unidirectional antenna.
97
Alice is a new hire at Adatum Corp., and when she asks about wireless network access for her laptop, she is given an SSID and a WPA2 passphrase. Later, in the lunchroom when she tries to connect her laptop to the network, she cannot see the SSID she was given in the available networks list, although she can see other networks. What should Alice do next to try to resolve the problem?
A. Type in the WPA2 passphrase.
B. Type the SSID in manually.
C. Move closer to the wireless access point.
D. Move away from the microwave in the lunchroom.
B. Type the SSID in manually.
It is possible that the wireless access point has been configured not to broadcast the network's SSID as a security measure, so Alice should first attempt to access it by typing the SSID in manually. She would not be able to type in the WPA2 passphrase until she is connecting to the SSID. Moving the laptop closer to the access point or away from possible sources of electromagnetic interference might be solutions to the problem, but they should not be the first thing Alice tries.
98
Alice is a new hire at Adatum Corp., and when she asks about wireless network access for her laptop, she is given an SSID and a passphrase. She is also told that she must add the SSID manually. Later, she types in the SSID she was given, and the computer prompts her to select a security type. Not knowing which option to choose, she selects 802.1x, because it sounds as though it should be the most secure. However, this option does not enable her to enter her passphrase, so she selects another option, WEP, and is able to type in the passphrase. However, her laptop says she “Can't connect to this network.” Which of the following is the most likely cause of Alice's problem?
A. Overcapacity
B. Distance limitations
C. Frequency mismatch
D. Security type mismatch
D. Security type mismatch
The most likely cause of Alice's problem is that she has selected an incorrect security type. Wired Equivalent Privacy (WEP) is still provided as an option on many wireless devices, but it has long since been found to be insecure and is almost never used. Alice should try selecting the other security types that enable her to enter her passphrase, such as Wi-Fi Protected Access II (WPA2). Although the other options are possible causes of the problem, security type mismatch is the most likely cause.
99
Ralph purchases some 802.11a wireless network adapters for desktop computers at a yard sale, which he intends to use on his 802.11g home network. He installs one of the adapters in a computer and attempts to connect it to the network, but he can't see his SSID. He tries a different adapter, thinking the first one might be broken, but that one does not work either. What can Ralph do to resolve the problem and connect the computer to his network?
A. Move the computer closer to the access point.
B. Configure the access point to use the 5 GHz frequency.
C. Manually enter the SSID in the computer's client software.
D. Nothing. 802.11a equipment cannot connect to an 802.11g network.
D. Nothing. 802.11a equipment cannot connect to an 802.11g network.
Wireless LAN equipment built to the 802.11a standard can only use the 5 GHz frequency. However, an 802.11g access point can only use the 2.4 GHz frequency. Therefore, the network adapters cannot connect to Ralph's access point.
100
Ralph is responsible for a wireless LAN that consists of an 802.11n 2x2 access point and laptop computers with a variety of network adapters. Some of the laptops support 802.11n, most support 802.11g, and a few older models have 802.11a adapters. The wireless LAN is located in a large office building with many other wireless networks, and Ralph is having trouble finding a channel on the 2.4 GHz band that is not congested with traffic. Scanning the 5 GHz band, he finds relatively little traffic, so he reconfigures the access point to use a 5 GHz channel. The result is that some of the laptops are able to connect to the network, whereas others are not. What is the most likely reason for the connection failures, and what must Ralph do to enable all of the laptops to connect to the wireless network?
A. The 5 GHz band does not support automatic channel selection. Ralph must configure each laptop to use the same channel as the access point for all the laptops to connect successfully.
B. The 802.11g standard does not support communication using the 5 GHz band. Ralph must configure the access point to support 2.4 GHz for all the laptops to connect successfully.
C. The 5 GHz band does not support MIMO communications, so the 802.11n laptops are unable to connect to the network. Ralph must replace the access point with an 802.11g unit for all the laptops to connect successfully.
D. The 802.11a standard does not support communication using the 5 GHz band. Ralph must replace the network adapters in those laptops with newer models for them to connect successfully.
B. The 802.11g standard does not support communication using the 5 GHz band. Ralph must configure the access point to support 2.4 GHz for all the laptops to connect successfully.
The 802.11b and 802.11g standards do not support 5 GHz communications. Configuring the access point to support 2.4 GHz is the only way for the 802.11g computers to connect to the network. The 5 GHz band does support automatic channel selection, so there is no need to configure the channel on each laptop manually. The 5 GHz band does support MIMO, and the 802.11n laptops should be able to connect. Replacing the adapters with 802.11g will prevent them from connecting, as that standard does not support 5 GHz communications. The 802.11a standard does support the 5 GHz band, and those laptops should be able to connect.
101
Alice is the administrator of a wireless network that has client computers in a number of small offices, all located on the same floor of an office building built in the mid-twentieth century. The network has an IEEE 802.11g access point located at the approximate center of the floor. Workstations in most of the rooms connect to the network at 54 Mbps, but the computers in one particular room rarely connect at speeds above 11 Mbps. Which of the following might be the cause of the problem?
A. The computers in the problematic room are configured to use a different wireless encryption protocol than the access point.
B. The computers in the problematic room are experiencing an SSID mismatch.
C. The network adapters in the problematic computers support IEEE 802.11a, not 802.11g.
D. The room containing the problematic computers might be at the limit of the access point's range.
D. The room containing the problematic computers might be at the limit of the access point's range.
As wireless computers move farther away from the access point, their signals attenuate (weaken) and the maximum speed of their connections drops. If the computers were using a different encryption protocol than the access point, there would be no connection at all, not a diminished connection speed. An SSID mismatch would cause the computers to connect to a different network, not necessarily connect at a slower speed. If the computers had 802.11a adapters, they would fail to connect to the access point at all, because 802.11a requires the use of the 5 GHz frequency band, and 802.11g uses 2.4 GHz.
102
Which of the following terms describes the progressive weakening of transmitted signals as they travel along a network medium?
A. Absorption
B. Latency
C. Attenuation
D. Crosstalk
C. Attenuation
Attenuation is the weakening of a signal as it travels long distances, whether on a wired or wireless medium. The longer the transmission distance, the more the signal weakens. Absorption is the tendency of a wireless signal to change as it passes through different materials. Latency is a measurement of the time it takes for a signal to travel from its source to its destination. Crosstalk is a type of interference that occurs on wired networks when a signal bleeds over to an adjacent wire.
103
Which of the following is not a potential solution for an IEEE 802.11g wireless computer that has intermittent problems connecting to an IEEE 802.11b/g access point?
A. Install a higher gain antenna on the access point.
B. Replace the access point with a model that supports 802.11n.
C. Move the computer closer to the access point.
D. Change the channel used by the access point..
B. Replace the access point with a model that supports 802.11n.
Replacing the access point with an 802.11n model is not going to have any effect at all unless you upgrade the computer's network adapter as well. Installing a higher gain antenna on the access point can improve its range, enabling the computer to connect more readily. Moving the computer closer to the access point can strengthen the signal, enabling it to connect more reliably. Changing the channel on the access point to a lesser used one can enable the computer to connect more easily.
104
Alice is supporting a network that consists of four internal local area networks (LANs) with 50 users each. Each internal LAN uses twisted pair Gigabit Ethernet links that connect the users to a switch. Each of the four switches connects to a backbone router. All of the routers connect to the same backbone network, which has a single additional router to connect the company's network to the Internet, using a T-1 link. Users on one of the internal LANs are complaining that, when they came in this morning, they could not access the Internet or the other internal LANs, although they could access local resources with no problems. Which network component is the likeliest source of the problem in this scenario?
A. The router connecting the problem LAN to the backbone
B. The Internet router
C. The switch on the problem LAN
D. The cable on the backbone network
A. The router connecting the problem LAN to the backbone
In this scenario, only users on one LAN are experiencing problems connecting to the Internet and other internal LANs. This isolates the problem to a component within that LAN only. Since users can connect successfully to local resources, the problem doesn't lie within the individual computers,the switch that connects the users to the network, or the backbone network cable. The likeliest problem is in the router connecting problem LAN to the backbone network. Since users on the other internal LANs are not reporting problems connecting to the Internet, the problem most likely doesnot involve the Internet router.
105
Alice is supporting a network that consists of four internal local area networks (LANs) with 50 users each. Each internal LAN uses twisted pair Gigabit Ethernet links that connect the users to a switch. Each of the four switches connects to a backbone router. All of the routers connect to the same backbone network, which has a single additional router to connect the company's network to the Internet. Users on all of the internal LANs are complaining that, when they came in this morning, they could not access the Internet, although they could access resources on all of the LANs with no problems. Which network component is the likeliest source of the problem in this scenario?
A. The router connecting the problem LAN to the backbone
B. The Internet router
C. The switch on the problem LAN
D. The cable on the backbone network
B. The Internet router
In this scenario, all of the internal users are experiencing problems connecting to the Internet, so the router that provides access to the Internet is the suspected component. Since users can connect to resources on the internal LANs, the problem probably is not in any of the routers connecting the LANs to the backbone or the backbone cable itself. This also eliminates the probability that the switches on the LANs are the problem.
106
You have three virtual LANs (VLAN2, VLAN3, and VLAN4) with each implemented on three switches. A single router provides routing among the VLANs. All of the VLAN2 users connected to a common switch are complaining that they can't access resources on other hosts within their own VLAN or on VLAN3 and VLAN4. Before today, they could connect to local and remote resources with no problem. What is the likeliest cause of the service interruption?
A. The router is malfunctioning and not routing among the VLANs.
B. VLAN2 is misconfigured.
C. The common switch to which the VLAN2 users are connected is not functioning.
D. VLAN3 and VLAN4 are misconfigured.
C. The common switch to which the VLAN2 users are connected is not functioning.
In this scenario, some, but not all, users on VLAN2 can't connect to local and remote resources. Since users connected to other switches within the same VLAN and on other VLANs are not reporting any problems, the router is not the issue. This also excludes a VLAN2 configuration problem, because this would affect the VLAN2 users on all of the switches. VLAN3 and VLAN4 users can communicate through the router, so they are also not the problem. The likeliest problem is the common component, which is the switch to which the VLAN2 users experiencing the outage are connected.
107
Ralph has a wired home network with three Windows computers, a switch, and a cable modem/router that provides access to the Internet. One of the computers is able to connect to the other two, but it cannot connect to the Internet. Which of the following configuration parameters on the malfunctioning computer will Ralph most likely have to change to resolve this problem?
A. IP address
B. Subnet mask
C. Default gateway
D. MAC address
C. Default gateway
The problem is most likely the default gateway address, which directs all traffic intended for the Internet to the cable modem/router. If that address is incorrect, the traffic will never reach the router. Because the computer can access the other two systems on the local network, the IP address and subnet mask are not the problem. It is not necessary (and not always possible) to change the MAC address on a Windows workstation.
108
Ralph has a wired home network with three Windows computers, a switch, and a cable modem/router that provides access to the Internet. All three computers are able to access the Internet, but none of them can access file system shares on the others. Which of the following is the most likely cause of the problem on the three network computers?
A. Incorrect IP addresses
B. Incorrect Subnet mask
C. Incorrect default gateway address
D. Incorrect ACL settings
D. Incorrect ACL settings
The problem is most likely incorrect ACL settings. Because the computers are all able to access the Internet, their TCP/IP settings, including their IP addresses, subnet mask, and default gateway address, must be correct. However, if the users do not have the correct permissions in the access control lists (ACLs) of the file system shares, they will not be able to access the shares over the network.
109
A user reports to Ralph that he cannot access the Internet, although he is able to connect to computers on the local network. Ralph runs ipconfig /all on the user's workstation and examines the output. Which of the following is the most likely explanation for the user's problem, based on these ipconfigresults?
A. The Subnet Mask setting is incorrect.
B. The Default Gateway setting is incorrect.
C. The DNS Servers setting is located on another network.
D. DHCP is not enabled.
B. The Default Gateway setting is incorrect.
The Default Gateway setting should contain the address of a router on the local network that provides access to other networks, such as the Internet. In this case, therefore, the Default Gateway address should be on the 192.168.4.0 network, but it contains an address on the 192.168.6.0" network, which is not local. Therefore, the user can only access systems on the 192.168.4.0 network. The Subnet Mask setting must be correct, or the user would not be able to access any other systems. Unlike the default gateway, the DNS server does not have to be on the local network, so the address shown can be correct. DHCP is not necessary to access the Internet.
110
Ralph is troubleshooting a workstation that cannot access the network. The workstation is plugged into a wall plate that should provide it with access to a DHCP-equipped network using the 192.168.4.0/24 network address. No one else on that network is reporting a problem. Ralph checks that the patch cable is properly plugged into the workstation and the wall plate, which they are, and then runs ipconfig /allon the user's workstation and examines the output. Which of the following could be the explanation for the user's problem, based on these ipconfig results?
A. The Subnet Mask is incorrect.
B. The Default Gateway address is missing.
C. The DHCP scope is exhausted.
D. The DNS server addresses are incorrect.
C. The DHCP scope is exhausted.
The 169.254.203.42 address assigned to the workstation is from the 169.254.0.0/16 network address assigned to Automatic Private IP Addressing (APIPA), a standard for the assignment of IP addresses to DHCP clients when they cannot obtain an address from a DHCP server. Since no one else is experiencing a problem, the DHCP server is presumably functioning. The Subnet Mask value is correct for an APIPA address, and APIPA does not provide Default Gateway or DNS server addresses. Therefore, an exhausted DHCP scope is the only one of the explanations provided that could be the cause of the problem.
111
Ralph is troubleshooting a workstation that cannot access the network. The workstation is plugged into a wall plate that should provide it with access to a DHCP-equipped network using the 192.168.32.0/20 network address. Ralph checks that the patch cable is properly plugged into the workstation and the wall plate, which they are, and then runs ipconfig /all on the user's workstation and examines the output. Which of the following could be the explanation for the user's problem, based on these ipconfigresults?
A. The IPv4 Address setting is incorrect.
B. The Subnet Mask setting is incorrect.
C. The Default Gateway setting is incorrect.
D. The DNS Servers setting is located on another network.
B. The Subnet Mask setting is incorrect.
For a computer connected to the 192.168.32.0/20 network, the Subnet Mask value should be 255.255.240.0, not 255.255.255.0, as shown in the ipconfig output. The IPv4 Address, Default Gateway, and DNS Servers settings are appropriate for the network.
112
Ralph is troubleshooting a workstation that cannot access the network. The workstation is plugged into a wall plate that should provide it with access to a DHCP-equipped network using the 192.168.4.0/24 network address. Ralph checks that the patch cable is properly plugged into the workstation and the wall plate, which they are, and then runs ipconfig /all on the user's workstation and examines the output. Which of the following could be the explanation for the user's problem, based on these ipconfigresults?
A. The workstation could not connect to a DHCP server.
B. There is a rogue DHCP server on the network.
C. The workstation is not configured to use DHCP.
D. The IP address assigned by the DHCP server has expired.
B. There is a rogue DHCP server on the network.
The DHCP client on the workstation is enabled, but the IP address assigned to the workstation is not from the 192.168.4.0/24 network. The assigned address is not an APIPA address, nor is it expired, so the only conclusion is that there is a rogue DHCP server on the network assigning addresses from a wholly different subnet.
113
Alice has been asked to update an accounts receivable spreadsheet with information about the day's incoming payments, a task she has never performed before. After locating and opening the spreadsheet on the network server, she types in her new information, but when she attempts to save the changes, she receives an error message that directs her to save the file on her local drive instead of the network server. Which of the following is the probable cause of the problem?
A. Blocked TCP/UDP ports
B. Incorrect filesystem ACL settings
C. Incorrect firewall settings
D. Untrusted SSL certificate
B. Incorrect filesystem ACL settings
Because Alice is able to access the server and open the spreadsheet file, the problem is not related to blocked ports, firewall settings, or an untrusted certificate. The problem is most likely that though she has the necessary filesystem access control list (ACL) permissions to open and read the file, she does not have the permissions needed to modify it.
114
Ralph is a network administrator attempting to use his workstation to remote into a web server called WebServ1 on the perimeter network. However, the remote desktop client software is unable to establish a connection to the server. Ralph can see all of the computers on his local network and on the perimeter network. He tries using the ping utility to test the WebServ1’s TCP/IP functionality, and the ping test is successful. Ralph then calls his colleague Ed and has him try to connect to WebServ1 using the same remote access tool. Ed connects successfully. Which of the following could be the cause of the problem Ralph is experiencing?
A. Name resolution failure
B. Unresponsive service on the web server
C. Blocked TCP/UDP ports on the web server
D. Incorrect firewall settings on Ralph's workstation
D. Incorrect firewall settings on Ralph's workstation
Because Ed can connect to WebServ1 successfully, the problem is not an unresponsive service or blocked ports on the server. The problem is not a name resolution failure because Ralph can successfully ping WebServ1 by name. Therefore, of the options listed, the only possible problem must be that the firewall on Ralph's workstation is not configured to allow the remote desktop client's traffic out.
115
A user calls the company's IT help desk to report that she has received an error message on her Windows workstation. The error states that her computer has an IP address that is duplicated on the network. Ralph is concerned that there might be a configuration problem with the DHCP servers on the network. He suspects that there are DHCP servers configured with scopes that overlap, resulting in two DHCP servers assigning the same IP addresses to different clients. He is worried that they are about to receive a flood of calls reporting the same problem. Alice reassures Ralph, telling him that it cannot be a DHCP problem and that there must be two computers that are manually configured with the same IP address. How does Alice know this?
A. Because Windows computers check the routing table before accepting an IP address from a DHCP server
B. Because DHCP servers use DNS queries to check for duplicate IP addresses
C. Because DHCP clients use ARP broadcasts to check for duplicate IP addresses
D. Because it is only possible to have one DHCP server on a given subnet
C. Because DHCP clients use ARP broadcasts to check for duplicate IP addresses
When a Dynamic Host Configuration Protocol (DHCP) client is offered an IP address by a DHCP server, the client broadcasts Address Resolution Protocol (ARP) requests using that address before accepting it. If another computer on the local network is using the offered address, the computer responds to the ARP request and the DHCP client declines the address. The DHCP server then offers another address. DNS queries and routing table checks are not reliable means of checking for duplicate IP addresses. It is possible to have two DHCP servers on the same local network, but they must be configured with scopes that do not overlap.
116
A user, Ed, is reporting what appear to be intermittent traffic interruptions on his workstation. Sometimes he receives responses to his server requests, and sometimes not. It doesn't seem to be an Internet issue, becausethe problem also occurs with local server requests. While troubleshooting the problem, Ralph performs a series of packet captures and analyzes the network traffic. He discovers that all of the request messages generated by Ed's workstation have responses on the network, but in some cases, the responses are going to a workstation other than Ed's. Which of the following conditions could be causing this to happen?
A. Duplicate IP addresses
B. Blocked TCP/UDP ports
C. Duplicate MAC addresses
D. Incorrect host firewall settings
C. Duplicate MAC addresses
If someone on the network is spoofing the MAC address of Ed's workstation, the MAC address table in the switch handing the network traffic might be continually changing as packets from each computer reach the switch. This could cause some of the response packets to be forwarded to Ed's workstation and some to the spoofer's workstation. Duplicate IP addresses would not cause this problem because they would be detected by the operating system. Blocked ports and incorrect firewall settings could prevent Ed from receiving responses, but they would not be sent to another workstation.
117
A user calls Alice at the IT help desk and reports that she is having intermittent problems accessing both local servers and Internet websites. Which of the following potential problems can Alice rule out immediately?
A. Duplicate MAC addresses
B. Duplicate IP addresses
C. Malfunctioning router
D. Malfunctioning DNS serve
B. Duplicate IP addresses
Operating systems detect duplicate IP addresses immediately and display error messages or notifications on the computers involved. Therefore, the user with the problem would have been informed immediately if another system was using her IP address. All of the other options are possible causes of the problem that are more difficult to troubleshoot.
118
The entire network at Adatum Corp. is unable to access the Internet. All of the users throughout the network are complaining that their browsers are displaying DNS failure messages. The company does not have an in-house network administrator, so they call Ralph at his consulting firm. Which of the following should be the first question that Ralph asks in his attempt to pinpoint the location of the malfunction?
A. What browser are the users running?
B. Where is the DNS server located?
C. What technology is used to provide access to the Internet?
D. What sites are the users attempting to access?
B. Where is the DNS server located?
The users’ browsers are failing to resolve the host names of the requested web sites into IP addresses, which they must do before they can connect to the web servers. By asking where the company's DNS server is located, Ralph can determine if the problem is the DNS server itself or the router that provides access to the Internet. If the DNS server is located on Adatum's company network, then the DNS server could be failing to resolve the website names. However, the DNS server could be located on the Internet service provider's network, in which case the problem might be in the router that provides access to the ISP's network.
119
Ed is implementing a web server farm on his company's network and has created a perimeter network on which the web servers will be located. The perimeter network is using the network IP address 192.168.99.0/24. He has also installed a router connecting the perimeter network to the internal network, which uses the 192.168.3.0/24 network address. The IP addresses of the router's interfaces are 192.168.3.100 and 192.168.99.1. Ed needs to access the web servers from his Windows workstation on the internal network, but right now, he cannot do so. Because he needs to have a different router specified as his default gateway, Ed decides to add a route for the perimeter network to his computer's routing table. Which of the following commands will create a routing table entry that enables Ed to access the perimeter network?
A. route add 192.168.99.0 MASK 255.255.255.0 192.168.3.100
B. route add 192.168.3.0 MASK 255.255.255.0 192.168.3.100
C. route add 192.168.99.1 MASK 255.255.255.0 192.168.3.0
D. route add 192.168.3.100 MASK 255.255.255.0 192.168.99.0
A. route add 192.168.99.0 MASK 255.255.255.0 192.168.3.100
The correct syntax for the Windows route add command is to specify the destination network address, followed by the subnet mask for the destination network, followed by the address of the router interface on the local network that provides access to the destination network. The other options do not specify the correct addresses in the syntax.
120
Alice has recently created a new perimeter network for the company's web server cluster, along with a router to connect it to the internal network. When she is finished, she sends Ralph an email instructing him to run the following command on his Windows workstation so that he can access the servers on the perimeter network. What function does the IP address 192.168.87.226 perform in this command?
route add 192.168.46.0 MASK 255.255.255.0 192.168.87.226
A. 192.168.87.226 is the address of Ralph's workstation.
B. 192.168.87.226 is the network address of the perimeter network.
C. 192.168.87.226 is the address of one of the router's interfaces.
D. 192.168.87.226 is the address of web server cluster.
C. 192.168.87.226 is the address of one of the router's interfaces.
The correct syntax for the Windows route add command is to specify the destination network address, followed by the subnet mask for the destination network, followed by the address of the router interface on the local network that provides access to the destination network. Therefore, 192.168.87.226 is the address of the router interface on the internal network, where Ralph's workstation is located.
121
To save the company money and to provide some new hires with Gigabit Ethernet connectivity, Ralph has installed some new Category 5e cable runs, connecting his company's datacenter with a newly rented office at the far end of the building. However, the new users are complaining of intermittent connectivity problems. The company brings in a cabling contractor to investigate, and his diagnosis is attenuation. Which of the following solutions will most likely be a sure solution to the problem?
A. Repull the runs using Category 6 cable.
B. Shorten the cable runs.
C. Configure the hardware to run at a slower speed.
D. Install high-end network adapters in the workstations.
B. Shorten the cable runs.
Attenuation is the weakening of the signals as they traverse the network medium. In this case, it is most likely the result of cable runs that exceed the 100 meter maximum defined in the Ethernet twisted pair specification. Therefore, shortening the cable runs will be likely to solve the problem. All of the Ethernet twisted pair specifications have a 100 meter maximum length, so running the network at a slower speed, installing a higher grade cable, and installing higher end network adapters might have no effect if the runs are overly long.
122
Alice's network has been experiencing intermittent service slowdowns and outages ever since the company moved into their new building. She has tried every troubleshooting procedure she can think of and hasn't been able to determine the cause. One particularly irritating user, hoping to be the squeaky wheel that gets the grease, has taken to calling Alice every time he experiences a problem. One day, as she is working in the datacenter, Alice notices that the user calls her every time she hears an additional humming noise begin. After examining the doors in the hallway, Alice realizes that the racks containing her switches are located right next to the elevator machinery room. Which of the following conditions is probably causing the network communication problem?
A. EMI
B. NEXT
C. FEXT
D. Attenuation
A. EMI
Elevator machinery, fluorescent light fixtures, and other electrical devices in an office environment can generate magnetic fields, resulting in electromagnetic interference (EMI). When copper-based cables are located too near to such a device, the magnetic fields can generate an electric current on the cable that interferes with the signals exchanged by network devices. If the network users experience a problem every time the elevator machinery switches on, EMI is a likely cause of the problem. Near end crosstalk (NEXT), far end crosstalk (FEXT), and attenuation can all cause intermittent network communication problems, but they cannot be caused by elevator machinery.
123
Ed has configured his workstation to use IPsec encryption for network communications. Which of the following tools can he use to verify that his network traffic is encrypted?
A. Multimeter
B. Packet sniffer
C. Port scanner
D. Protocol analyzer
D. Protocol analyzer
A protocol analyzer is a tool that enables a user to view the contents of packets captured from a network. In Ed's case, if IPsec is properly implemented, he should be able to see that the data in packets captured from his workstation is encrypted. A packet sniffer is a tool that captures packets for the purpose of traffic analysis, but cannot view their contents. In practice, however, packet sniffer and protocol analyzer capabilities are usually integrated into a single tool. A port scanner examines a system, looking for open TCP and UDP ports, and a multimeter is a tool that reads voltages on electrical circuits. Neither of these tools can examine packet contents.
124
Which of the following statements describes the difference between a packet sniffer and a protocol analyzer?
A. A packet sniffer captures network traffic, and a protocol analyzer examines packet contents.
B. A protocol analyzer captures network traffic, and a packet sniffer examines packet contents.
C. A packet sniffer only captures the local workstation's traffic, whereasa protocol analyzer can capture all the traffic on the network.
D. There is no difference. Packet sniffers and protocol analyzers perform the same functions.
A. A packet sniffer captures network traffic, and a protocol analyzer examines packet contents.
A packet sniffer is a tool that captures packets for the purpose of traffic analysis, but cannot view their contents. A protocol analyzer is a tool that enables a user to view the contents of packets captured from a network. In practice, however, packet sniffer and protocol analyzer capabilities are usually integrated into a single tool. Both tools can function in promiscuous mode to capture packets from an entire network.
125
Ralph is experiencing poor performance on his home 802.11n wireless network. Ralph lives in a large apartment complex, and when he runs a Wi-Fi analyzer, he sees many other nearby networks using the often-recommended channels 1, 6, and 11 on the 2.4 GHz frequency. Using the 5 GHz frequency is not an option for Ralph's equipment. What should Ralph do to improve his network performance?
A. Configure his equipment to use channel 2
B. Configure his equipment to use channel 5
C. Configure his equipment to use channel 9
D. Configure his equipment to use channel 10
C. Configure his equipment to use channel 9
The 2.4 GHz band used by wireless LANs (WLANs) consists of channels that are 20 (or 22) MHz wide. However, the channels are only 5 MHz apart, so there is channel overlap that can result in interference. Channels 1, 6, and 11 are the only channels that are far enough apart from each other to avoid any overlap with the adjacent channels. This is why they are often recommended. However, in Ralph's case, these channels are too crowded with other networks. Ralph should therefore use a channel that is as far as possible from the crowded ones. Channels 2, 5, and 10 are all immediately adjacent to a crowded channel, but channel 9 is at least two channels away from the nearest crowded channel. Therefore, Ralph should configure his equipment to use channel 9.
126
A user calls Alice at the help desk to report that he cannot access the Internet. He can access systems on the local network, however. Alice examines the routing table on the user's workstation, and sees the following. Which of the following statementsexplains why the user cannot access the Internet?
A. The routing table contains a loopback address.
B. The routing table does not specify a default gateway address.
C. The routing table does not specify a DNS server address.
D. The routing table contains two different routes to the 224.0.0.0 network.
B. The routing table does not specify a default gateway address
To access the Internet, the workstation's routing table must include a default gateway entry, which would have a Network Destination value of 0.0.0.0. A workstation's routing table does not specify the address of a DNS server. The loopback and 224.0.0.0 multicast addresses are normal routing table entries.
127
Ralph is setting up a network connection for the company's new vice president, who is supplying his own laptop. He plugs the computer into the wall plate, and the link pulse LED lights up. Then, back in the datacenter, he uses a patch cable to connect the corresponding port in the patch panel to a port in the network switch. Later, the VP calls Ralph to report that data transfers between his laptop and the network servers are extremely slow. Which of the following could explain the problem?
A. There is a duplex mismatch between the laptop and the network switch.
B. Ralph used a crossover cable to connect the laptop to the wall plate.
C. The switch port is disabled.
D. The network adapter drivers on the laptop are outdated.
A. There is a duplex mismatch between the laptop and the network switch.
A duplex mismatch is the most likely of the options. Ethernet running over twisted pair cable, in its original half-duplex mode, detects collisions by looking for data on the transmit and receive pins at the same time. In full-duplex mode, data is supposed to be transmitted and received at the same time. When one side of a connection is configured to use full duplex and the other end is configured to use half duplex, the full-duplex communications on the one side look like collisions to the half-duplex side. The half-duplex adapter transmits a jam signal as a result of each collision, which causes the full-duplex side to receive an incomplete frame. Both sides then start to retransmit frames in a continuing cycle, causing network performance to diminish drastically. If the problem was a crossover cable or a disabled switch port, the link pulse LED would not light. Outdated drivers would not be likely to slow network performance, and if they did, the slowdown would be minor.
128
Ralph is deploying an 802.11n wireless network for a client that calls for the best possible security without deploying additional servers. When setting up the wireless access point, Ralph disables SSID broadcasts, selectsWi-Fi Protected Access security with preshared keys (WPA-PSK), and configures MAC address filtering. Which of the following statements about the security of this arrangement is true?
A. The configuration is as secure as Ralph can make it with the specified equipment.
B. Ralph should not disable SSID broadcasts, sincethis prevents users from connecting to the network.
C. Ralph should not use MAC address filtering, becauseit exposes MAC addresses to possible attacks.
D. Ralph should use Wi-Fi Protected Access II (WPA2) instead of WPA, because it is more resistant to certain types of attacks.
D. Ralph should use Wi-Fi Protected Access II (WPA2) instead of WPA, because it is more resistant to certain types of attacks.
WPA has been found to be vulnerable, and WPA2 was designed to address those vulnerabilities, so Ralph should use WPA2 instead of WPA. Suppressing SSID broadcasts does not prevent users from connecting to the network, and MAC filtering strengthens security without exposing MAC addresses to undue risk.
129
While working in her company's datacenter, Alice notices that the LEDs on most of the network switch ports are green, but there are several that are orange. Alice asks several people why this is so and receives several different answers. Which one of the following answers is correct?
A. The orange LEDs indicate that no device is connected to the switch port.
B. The orange LEDs indicate that the connected device is experiencing an excessive number of collisions.
C. The orange LEDs indicate that the device is connected to the switch at a relatively slow speed.
D. The orange LEDs indicate that the connected devices are other switches, rather than workstations.
C. The orange LEDs indicate that the device is connected to the switch at a relatively slow speed.
Green LEDs indicate the device is running at the full speed supported by the switch, whereas orange LEDs indicate that the device is running at a reduced speed. If no device is connected, the LED does not illuminate at all. The LED does not indicate the occurrence of collisions or the type of device connected to the port.
130
Ralph recently bought an old 10Base-T Ethernet hub at a garage sale and wants to use it to connect his various computers into a home network. He plugs three computers into the hub and finds that althoughtwo of his older computers can communicate with each other, his newest computer cannot connect to the network. Which of the following tasks will most likely resolve the problem?
A. Configure the hub to run at 10 Mbps.
B. Configure the hub to run at 100 Mbps.
C. Configure the computer's network adapter to run at 10 Mbps.
D. Configure the computer's network adapter to run at 100 Mbps.
C. Configure the computer's network adapter to run at 10 Mbps.
Ralph's new computer is probably equipped with a network adapter that supports at least Fast Ethernet (100Base-TX). Fast Ethernet and newer network adapters support auto negotiation of the connection speed, but 10Base-T does not. Therefore, if the computer tries to negotiate a connection speed with the 10Base-T hub, it will fail and run at its default speed, which the hub does not support. By manually configuring the adapter in the computer to run at 10 Mbps, it should be able to communicate with the network. Setting the computer's adapter to run at 100 Mbps will not change anything. It is not possible to change the speed of a 10Base-T hub.
131
Alice is troubleshooting a problem that some users are having connecting to an application server on the local network. While testing connectivity using the ping tool, she discovers that she can ping the server successfully using its computer name, but pinging the computer's fully qualified domain name (FQDN) fails. Which of the following is most likely the source of the problem?
A. DNS
B. DHCP
C. EMI
D. ACL
A. DNS
Only DNS servers perform FQDN resolutions, so that is likely to be the source of the problem. It is possible to ping a device on the local network using its computer name without the use of DNS. Electromagnetic interference (EMI) would inhibit all network communication, and access control lists have no effect on ping tests.
132
Users on Ed's 802.11n wireless network are dropping their connections intermittently. Which of the following might help to resolve the problem?
A. Restart the wireless access point
B. Change the network's SSID
C. Change the channel the devices are using
D. Change the wireless security protocol
C. Change the channel the devices are using
If the users are losing their connections due to interference from other types of devices, changing the channel alters the frequency the network uses and can enable it to avoid the interference. The other options are not likely to affect any condition that would cause users to drop their connections.
133
Alice's company is opening a new branch office, and Alice is responsible for building the Active Directory domain controller for that office. She installs a new Windows server and configures it as a domain controller and then ships it to the new office site. However, once it arrives and is connected to the home office network, the new domain controller fails to synchronize with the existing ones at the home office. Which of the following could be the cause of the problem?
A. Incorrect time
B. Server hardware failure
C. Duplicate IP addresses
D. Incorrect default gateway address
A. Incorrect time
If the time on the Active Directory domain controller at the new office is more than five minutes off of the time held by domain controller with the PDC Emulator role at the home office, then the new domain controller will not sync. Duplicate IP addresses or an incorrect default gateway address would prevent the new domain controller from connecting to the home office network. A server hardware failure would manifest as an outage far more serious than a domain controller synchronization issue.
134
A user calls Alice at the help desk to report that he cannot access the Internet. He can access systems on the local network, however. Alice examines the routing table on the user's workstation and sees the following. Which of the following commands must Alice run to correct the user's problem?
A. route add 0.0.0.0 MASK 0.0.0.0 192.168.2.37 METRIC 25 IF 192.168.2.99
B. route add 0.0.0.0 MASK 255.255.255.0 192.168.2.99 METRIC 25 IF 192.168.2.37
C. route add 192.168.2.0 MASK 255.255.255.0 192.168.2.99 METRIC 25 IF 192.168.2.37
D. route add 0.0.0.0 MASK 0.0.0.0 192.168.2.99 METRIC 25 IF 192.168.2.37
D. route add 0.0.0.0 MASK 0.0.0.0 192.168.2.99 METRIC 25 IF 192.168.2.37
To access the Internet, the workstation's routing table must include a default gateway entry. To create a default gateway entry in the routing table, you use the route add command with a Network Destination value of 0.0.0.0, a MASK value of 0.0.0.0, and the address of a router on the local network (in this case, 192.168.2.99). The entry must also have a METRIC value that is lower than the other entries in the table so that it will be used first.
135
Which of the following protocols does the traceroute utility on Unix and Linux systems use to test TCP/IP connectivity?
A. ICMP
B. HTTP
C. TCP
D. UDP
D. UDP
On Unix and Linux systems, the traceroute utility tests TCP/IP connectivity by transmitting User Datagram Protocol (UDP) messages. This is unlike the tracert utility on Windows systems, which uses Internet Control Message Protocol (ICMP) messages. Neither version uses TCP or HTTP.
136
Alice is working on an older network with a Windows Internet Name Service (WINS) server, a Domain Name System (DNS) server, and an Internet router. A user is complaining that he suddenly can't connect to hosts on other internal networks. The user isn't having problems connecting to resources on his local network or the Internet. Alice asks the user whether anything is new or has been changed on the computer and discovers that he recently changed some Internet Protocol (IP) parameters. What should Alice do next?
A. Verify that the router is up and running and properly configured.
B. Verify that the WINS server is up and running and properly configured.
C. Verify that the DNS server is up and running and properly configured.
D. Verify that the user's IP configuration settings are correct.
D. Verify that the user's IP configuration settings are correct.
Since only one user is reporting the problem, the user's computer is the likeliest source of the problem. The user has probably changed or removed the WINS server address. If the user is working with an incorrect WINS address, he can access local network resources but not resources on another internal LAN. Also, he can access resources on the Internet, which means the Internet router and the DNS server are not the problem.
137
Which of the following Linux commands produced the output shown in the figure?
A. netstat -ns microsoft.com
B. dig microsoft.com ns
C. nslookup microsoft.com
D. route -s microsoft.com
B. dig microsoft.com ns
The dig utility in Linux can display the authoritative DNS servers for a particular domain when you specify the domain name and the ns (name server) parameter. The netstat, nslookup, and routecommands cannot generate this particular output.
138
Ralph has begun to receive calls from users reporting that they cannot access the local network or the Internet. Ralph checks their computers and discovers that all of the users with a problem have IP addresses in the 169.254.0.0/16 network, which is not the address used on Ralph's network. Which of the following might be the cause of the problem?
A. The users have tried to modify their IP configuration settings.
B. There is a rogue DHCP server somewhere on the network.
C. The IP address leases assigned by the DHCP server have expired.
D. The users’ workstations have been infected by a form of malware.
C. The IP address leases assigned by the DHCP server have expired.
The 169.254.0.0/16 network is used by Automatic Private IP Addressing (APIPA), a standard that provides DHCP clients with an IP address when they cannot contact a DHCP server. Unknown to Ralph, the DHCP server on his network has been down for over a week, and the users’ IP address leases have begun to expire. This causes them to revert to APIPA addresses. Multiple users changing their IP addresses would not result in them all using the same network address. A rogue DHCP would not be likely to deploy APIPA addresses to clients. Malware infections that modify IP addresses are rare.
139
Alice receives a call in which a user reports that he is unable to send print jobs to the network-attached workgroup printer near his desk. Which of the following tasks should Alice perform first?
A. Reinstall the printer driver on the user's workstation.
B. Test network connectivity to the printer using the ping utility.
C. Examine the switches to which the user's workstation and the printer are connected.
D. Check to see if there are printer firmware upgrades available.
B. Test network connectivity to the printer using the ping utility
The first phase of the troubleshooting process is gathering information. Learning whether the printer is accessible over the network can help Alice to isolate the location of the problem and develop a theory of probable cause. Installing drivers, checking switches, and upgrading firmware are all part of a later phase in the troubleshooting process: testing a theory to determine the cause of the problem.
140
Several accounting consultants are working in Ed's office for the first time, and they are unable to connect to the 802.11gwireless network with their laptops. They are selecting the correct SSID from the Available Networks list, but they cannot connect, and there are no error messages of any kind. Which of the following tasks should Ed perform to try to resolve the problem?
A. Check the network adapters in the laptops for channel overlap.
B. Change the frequency used by the wireless access point from 2.4 GHz to 5 GHz.
C. Examine the area where the consultants are working for possible sources of signal interference.
D. Make sure that the consultants’ laptops are configured to use the correct wireless security protocol.
D. Make sure that the consultants’ laptops are configured to use the correct wireless security protocol.
The use of an incorrect wireless security protocol is a well-known source of errorless connection failures, so checking this will most likely enable Ed to locate the source of the problem. Channel overlap is a problem that Ed would check and resolve at the access point, not the users’ workstations. It is not possible to change the frequency on the access point because the 802.11g standard only supports the 2.4 GHz frequency. Although signal interference could conceivably be the cause for a connection failure, the users can see the network, so this is probably not the problem.
141
Ralph has installed a new Category 5e cable run himself. He has attached keystone connectors to both ends of the cable, mounted the office-side connector to a wall plate, and mounted the datacenter connector into a patch panel. Then he took a patch cord and connected the patch panel port to an open port in one of the network switches. However, the LED on the switch port does not light. What should Ralph do?
A. Repull the cable run using Category 6 cable.
B. Check the cable run for wiring faults.
C. Make sure the switch port is not disabled.
D. Plug a computer into the wall plate.
D. Plug a computer into the wall plate.
For the link pulse LED on the switch port to light up, there must be a completed connection between the switch and a computer at the other end. None of the other options will cause the LED to light.
142
A user calls Ed at the help desk to report that his computer is displaying a Duplicate IP Address error message. This puzzles Ed because all of the network workstations should be configured to obtain their IP addresses from DHCP servers. Ed asks the user if he has changed the TCP/IP configuration settings on the computer recently. The user says no. Ed then asks of anybody else uses the workstation. The user says no. However, when Ed runs the ipconfig /all commandon the user's workstation, he sees that the DHCP Enabled setting reads No. What should Ed do next?
A. Accuse the user of changing the TCP/IP settings and then lying about it.
B. Activate the DHCP client on the workstation and close the trouble ticket.
C. Begin an investigation into the possibility of a rogue DHCP server on the network.
D. Change the IP address on the workstation to one that is not already in use.
B. Activate the DHCP client on the workstation and close the trouble ticket.
Because Ed knows that the network workstations should be using DHCP to obtain their IP addresses, the best thing to do is to enable the DHCP client and close the ticket rather than configure the system with another static address. There is no indication that there is a rogue DHCP server on the network, since the workstation's DHCP client is disabled. This is not the first time that Ed has had a user lie to him, nor will it be the last. He should just let it go and work on addressing the problem.
143
Ralph is having trouble providing satisfactory wireless network performance to some executive offices at the far end of the building. The offices have heavy doors and insulated walls for sound dampening, and the occupants typically leave their doors closed during work hours. Which of the following types of radio signal interference is Ralph trying to overcome?
A. Reflection
B. Refraction
C. Diffraction
D. Absorption
D. Absorption
Absorption is a type of interference that occurs when radio signals have to pass through barriers made of dense materials, such as walls and doors. In this case, the construction of the barriers has made them more formidable. Reflection is when signals bounce off of certain surfaces, such as metal. Refraction is when signals bend as they pass through certain barriers, such as glass or water. Diffraction is when signals have to pass around barriers to reach a particular destination. All of these phenomena can weaken the radio signals used in wireless networking, but absorption is the primary problem for Ralph in this case.
144
Ralph is having trouble providing satisfactory wireless network performance to some executive offices at the far end of the building. The wireless access point is based on the 802.11g standard. The offices have heavy doors and insulated walls for sound dampening, and the occupants typically leave their doors closed during work hours. Which of the following actions can Ralph take to provide the users in this offices with better wireless network performance?
A. Install an additional access point nearer to the offices.
B. Modify the access point to use higher number channels.
C. Upgrade the access point to a model based on the 802.11n standard.
D. Configure the access point to disable SSID broadcasting.
A. Install an additional access point nearer to the offices.
The closer the users are to the access point, the stronger the signals will be. Installing an additional access point nearer to the executive offices will likely enable the signals to pass through the barriers more efficiently. The channel used by the access point, the standard on which the access point is based, and the broadcasting of SSID signals have no effect on the strength of the signals reaching the executive offices and will not resolve Ralph's problem.
145
It is Ralph's first day working for a consultancythat does network cable installations. His new boss hands him a spool of Category 6 cable, a large plier-like device, and a bag of little clear plastic components and tells him to “get started on fives and tens.” What is Ralph expected to do?
A. Pull cable runs
B. Create patch cables
C. Attach keystone connectors
D. Install a patch panel
B. Create patch cables
The plier-like device is a crimper, which cable installers use to attach RJ45 connectors, like those in the bag, to lengths of bulk cable. This is the process of creating patch cables, which are used to connect computers to wall plates and patch panels to switches. The boss is telling Ralph to start making patch cables in five and ten foot lengths. You do not use a crimper to attach keystone connectors, and the boss has not given Ralph the tools and components needed to pull cable runs or install a patch panel.
146
Alice is trying to provide users in a warehouse with wireless network connectivity for their tablets. The warehouse is a huge concrete structure with many internal cinderblock walls. Which of the following types of signal interference are inhibiting Alice's efforts?
A. Refraction
B. Reflection
C. Diffraction
D. Absorption
D. Absorption
Absorption is a type of interference that occurs when radio signals have to pass through barriers made of dense materials, such as concrete or cinderblock walls. The density of the material's molecular structure causes the radio signals to be partially converted to heat, which weakens them. Reflection is when signals bounce off of certain surfaces, such as metal. Refraction is when signals bend as they pass through certain barriers, such as glass or water. Diffraction is when signals have to pass around barriers to reach a particular destination. All of these phenomena can weaken the radio signals used in wireless networking, but absorption is the primary problem for Alice in this case.
147
Clients of Ralph's company are calling to complain that when they try to access the company's website, they see an error message stating that the website has an untrusted security certificate. They are afraid that they are connecting to an unprotected site or that the site has been taken over by hackers? What must Ralph due to address this problem?
A. Obtain an SSL certificate from a trusted third-party company.
B. Configure the web servers to generate a self-signed certificate.
C. Install a certification authority on one of the network servers.
D. Explain to the clients that it is safe to bypass the error message and proceed to the website.
A. Obtain an SSL certificate from a trusted third-party company.
For the website's Secure Socket Layer (SSL) certificate to be trusted, it must be signed by a source that both parties in the transaction trust. Many security firms are in the business of providing SSL certificates to companies that have provided them with confirmation of their identities. This is what Ralph must do to prevent the error message from appearing to the company's clients. Creating a self-signed certificate or installing a certification authority in-house are not sufficient and are probably already the cause of the problem. Users are not likely to be convinced that everything is all right.
148
Ed has installed a separate 802.11n wireless network for guest users working in his company's offices. The guest network is unsecured, and Ed has recently become aware that people outside the building are able to access it. It is not possible to move the access point, and it must run at maximum power to reach the entire building. Which of the following is the most convenient way to prevent users outside the building from accessing the guest network while leaving it available to users inside the building?
A. Change the passphrase daily.
B. Switch the network frequency.
C. Disable SSID broadcasting.
D. Implement MAC filtering.
C. Disable SSID broadcasting.
Moving the access point to the center of the building will keep as much of its operational range inside the structure as possible. If the signals still reach outside the building, Ed can reduce the power level of the access point until the network is only accessible inside.
Disabling SSID broadcasts will not defeat dedicated attackers, but it can prevent casual intruders from accessing the network. MAC filtering would require Ed to configure the access point with the MAC addresses of all devices that will access the network, which would be impractical in this case. The network is unsecured, so there is no passphrase to change, and a frequency change will have no effect on the problem.
149
Ralph is concerned that the IP address scope on his DHCP server is nearly exhausted. What happens to DHCP clients when there are no IP addresses left in the scope for assignment?
A. Clients are assigned a 0.0.0.0 address.
B. Clients self-assign APIPA addresses.
C. Client DHCP requests are forwarded to another DHCP server.
D. Clients are forced to share IP addresses.
B. Clients self-assign APIPA addresses.
When there are no IP addresses available in a DHCP scope, Automatic Private IP Addressing (APIPA) takes over, and the system self-assigns an address on the 169.254.0.0/16 network. Clients are not assigned a 0.0.0.0 address, nor are their requests forwarded to another DHCP server. Sharing IP addresses is not possible on a TCP/IP network.
150
Which of the following Unix/Linux tools is a packet analyzer?
A. iptables
B. nmap
C. tcpdump
D. pathping
C. tcpdump
The tcpdump utility is a command-line tool that captures network packets and displays their contents. The iptables, nmap, and pathping utilities cannot capture and analyze packets. iptables manages Unix/Linux kernel firewall rules, nmap is a port scanner, and pathping is a Windows route tracing tool.
151
Based on the output shown here, what is the average response time of the destination system?
A. 109.5
B. 104.33
C. 106
D. 99.66
B. 104.33
The destination system is the last one listed in the trace. By averaging the response times of 99, 106, and 108 ms, you can calculate the average response time: 104.33 ms.
152
Ralph has purchased some old 802.11b wireless networking equipment at a garage sale, which he plans to use to build a home network. When he installs the network adapters in his computers and sets up the access point, he finds that the connections between the devices are no faster than 11 Mbps. What can Ralph do to improve the performance of his network?
A. Nothing. The network is functioning at its top speed.
B. Change the channel used by the devices.
C. Move the computers closer to the access point.
D. Install a larger antenna on the access point.
A. Nothing. The network is functioning at its top speed.
The 802.11b standard calls for a maximum speed of 11 Mbps, so there is nothing that Ralph can do to increase his network's speed except purchase new equipment.
153
Which of the following Linux commands generated the output shown in the figure?
A. arp -a
B. arp -e
C. arp -d
D. arp -s
B. arp -e
Running the arp -e command on a Linux system displays the contents of the ARP cache in the format shown here. The arp -a command displays the cache using an alternative format. The arp -dcommand is for deleting cache entries, and the arp -s command is for creating cache entries.
154
Which of the following Windows commands enables you to create a new entry in the ARP cache?
A. arp -N
B. arp -d
C. arp -a
D. arp -s
D. arp -s
The arp -s command enables you to create a cache record specifying the MAC address and its associated IP address. The arp -N command enables you to display the ARP cache entries for a specified network interface. The arp -d command is for deleting cache entries. The arp -a command displays the entries in the ARP table stored in its cache.
155
Ralph is working on a new twisted pair network cable installation on which the individual cable runs were not been properly labeled as they were pulled. Ralph now has to trace each of the cable ends in the office area to the correct cable end in the data center and label them correctly. Which of the following tools should Ralph use to locate the correct cable in a bundle of unlabeled cable ends?
A. Cable certifier
B. Tone generator and locator
C. OTDR
D. Multimeter
B. Tone generator and locator
Ralph can use a tone generator and locator to locate the correct cable associated with each office connection. By connecting the tone generator to one end of a cable run, he can use the locator to find the other end. A cable certifier identifies a variety of cable performance characteristics, typically including cabling length, signal attenuation, and crosstalk. An optical time delay reflectometer is a device for measuring the lengths and other characteristics of fiber optic cables. A multimeter is a device for measuring the electric current on a copper cable.
156
Which of the following Windows command-line utilities produced the output shown here?
A. ping
B. tracert
C. netstat
D. arp
C. netstat
Running the Windows netstat command with the -e parameter displays Ethernet statistics, including the number of bytes and packets that have been transmitted and received. The ping, tracert, and arputilities are not capable of producing this output.
