Chapter 2 Networking Flashcards
You are using your laptop on the company network. In your web browser, you type www.google.com and press Enter. The computer will not find Google. You open the browser on your phone, and using your cellular connection, you can open Google without a problem. Your laptop finds internal servers and can print without any issues. What is the most likely reason you can’t open Google?
A) DNS server problem
B) DHCP server problem
C) Missing subnet mask
D) Duplicate IP address
A. The Domain Name System (DNS) server is responsible for resolving hostnames, such as www.google.com, to IP addresses to enable communication. If it’s not working properly or you can’t connect to it, you won’t be able to browse the Internet using friendly website names. Dynamic Host Configuration Protocol (DHCP) is used to assign IP addresses to network clients. The subnet mask might be incorrect, but it wouldn’t be missing, and a duplicate IP address would provide an error message stating that.
Which of the following network connectivity devices operates at Layer 2 of the OSI model?
A) Hub
B) Switch
C) Cable
D) Router
B. A switch operates at layer 2 of the open systems interconnection (OSI) model. Layers of the OSI model are (1) physical, (2) datalink, (3) network, (4) transport, (5) session, (6) presentation, and (7) application. The physical layer encompasses transmission media such as unshielded twisted pair (UTP), shielded twisted pair (STP), fiber optic, and so on. The datalink layer deals with transmitting frames on a LAN, so it includes the network interface card (NIC) and switch. Routers operate on OSI layer 3, because they transmit data between networks. Hubs work on OSI layer 1 because they merely connect devices in the same collision domain without regard to packet header information. The OSI model is not listed as an objective on the CompTIA A+ exam, but understanding it will help you understand network communications.
Which Wi-Fi standard is the fastest, operating in both the 2.4 and 5 GHz frequencies?
A) 802.11a
B) 802.11ac
C) 802.11ax
D) 802.11n
C. 802.11ax (Wi-Fi 6) is considered a replacement for 802.11ac (Wi-Fi 5). 802.11ac operates in the 5 GHz frequency, while 802.11ax can operate between 1 and 7.125 GHz frequencies, encompassing the 2.4 GHz and 5 GHz bands. 802.11ac can send data at over 1 Gbps, while 802.11ax can be several times that. 802.11a was adopted in 1999. It operates at 54 Mbps in the 5 GHz frequency band. 802.11n was adopted in 2008. It operates at 600 Mbps in both the 2.4 GHz and 5 GHz ranges.
Which type of IPv6 address identifies a single node on the network?
A) Multicast
B) Anycast
C) Unicast
D) Localcast
C. There are three types of addresses in IPv6: unicast, anycast, and multicast. A unicast address identifies a single node on the network. An anycast address refers to one that has been assigned to multiple nodes, and a packet will be delivered to one of them. A multicast address is one that identifies multiple hosts, and a packet will be sent to all of them.
What type of network covers large geographical areas and often supports thousands of users, often using lines owned by other entities?
A) LAN
B) WAN
C) PAN
D) MAN
B. A wide area network (WAN) covers large geographical areas and often supports thousands of users. A WAN can be for different locations of a single company, or a WAN may connect several different companies together to share information. WAN lines are often leased from a WAN provider. The Internet is considered to be a very large WAN. A local area network (LAN) covers a relatively small area such as a home or business. A personal area network (PAN) is usually used by one person and consists of their computer and its Bluetooth devices. A metropolitan area network (MAN) is similar to a WAN, but the area covered is much smaller, such as a university or a city.
Which of the following IP addresses is not routable on the Internet?
A) 10.1.1.1
B) 11.1.1.1
C) 12.1.1.1
D) 13.1.1.1
A. Private IP addresses are not routable on the Internet. IPv4 network numbers were arranged in classes, and classes A, B, and C each have their own private range. The private IP address range for Class A networks is 10.0.0.0/8. The /8 means that the first 8 bits of the subnet mask denote the network number. Expressing a subnet mask this way is known as CIDR (pronounced cider) notation. CIDR stands for classless interdomain routing. While the term CIDR doesn’t appear on the objectives for this CompTIA A+ exam, you may still run into it while working in IT.
Which network connectivity device does not forward broadcast messages, thereby creating multiple broadcast domains?
A) Hub
B) Switch
C) Bridge
D) Router
D. One of the key features of routers is that they break up broadcast domains. Broadcast traffic from one port of the router will not get passed to the other ports, which greatly reduces network traffic. Bridges, hubs, and switches will all forward broadcast packets.
your company just expanded and is leasing additional space in an adjacent office building. You need to extend the network to the new building. Fortunately, there is a conduit between the two. You estimate that the cable you need to run will be about 300 meters long. What type of cable should you use?
A) CAT-5e
B) CAT-7
C) CAT-8
D) MMF
D. Category 5, 6, and 7 UTP cables are limited to 100 meters, while Category 8 is limited to only 100 feet, so none of the UTP cables listed will work. You need fiber, and multimode fiber (MMF) can span distances of 300 meters. MMF is also known as OM1, OM2, OM3, OM4, and OM5. OM stands for optical mode. Specifications for each type of multimode fiber are available in the ISO/IEC 11801 standard.
Which of the following devices will be found in a telecommunications room and provides a means to congregate horizontal wiring, terminating each run in a female port?
A) Patch panel
B) Multiplexer
C) Rack U
D) Demarcation point
A. A patch panel can be found in a telecommunications room (also called a wiring closet), usually mounted in a networking rack. On the back will be connections to “punch down” wires into. On the front will be a female port, usually an RJ45 type. A multiplexer is a device that aggregates several connections into one. A rack U is simply a measurement of the height of a device mounted into a rack (e.g., my patch panel is 4U). Each U is equal to 1.75 inches. The demarcation point is where responsibility for a network changes from the ISP to its customer.
Which of the following IPv6 addresses is automatically assigned by the host when it boots and is only usable on the broadcast domain that it exists in?
A) 2000::/3
B) FC00::/7
C) FE80::/10
D) FF00::/8
C. An IPv6 address in the FE80::/10 range is called a link-local address and is similar to an IPv4 automatic private IP addressing (APIPA) address. (The 169.254.0.0/16 range in IPv4 is the APIPA range, used for automatic configuration if the host can’t locate a Dynamic Host Configuration Protocol [DHCP] server.) Link-local addresses are generated by the PC when it boots up. Packets using a link-local address cannot be forwarded by a router.
You need to configure a wireless router for an office network. The office manager wants new devices to be able to automatically join the network and announce their presence to other networked devices. Which service should you enable to allow this?
A) DHCP
B) NAT
C) QoS
D) UPnP
D. Universal Plug and Play (UPnP) is a standard designed to simplify the process of connecting devices to a network and to enable those devices to automatically announce their presence to other devices on the network. In a truly secure environment, UPnP would be disabled, but it is often left enabled on home networks. Dynamic Host Configuration Protocol (DHCP) automatically assigns an IP address to a device when it is powered on, attached to a network, and configured to obtain an address dynamically. Network address translation (NAT) is a feature of routers used to hide the IP addresses of computers on the local network side of the router from the other networks and computers on the outside of the network. Quality of Service (QoS) can be configured to give desired devices preference over others for using network bandwidth.
You are troubleshooting a computer with an IPv6 address that is in the FE80::/10 range. Which of the following statements are true? (Choose two.)
A) The computer will not be able to get on the Internet using that IP address.
B) The computer will be able to get on the Internet using that IP address.
C) The computer is configured with a link-local unicast address.
D) The computer is configured with a global unicast address.
A, C. Addresses in the FE80::/10 range are link-local unicast addresses. A link-local address is assigned to each IPv6 interface but is not routable on the Internet. If this is the only address the host has, it will not be able to get on the Internet.
You are configuring network hosts with static IP addresses. You have chosen to use a Class B network address. What is the default subnet mask that you should configure on the hosts?
A) 255.0.0.0
B) 255.255.0.0
C) 255.255.255.0
D) 255.255.255.255
B. The default subnet mask for Class B networks is 255.255.0.0, or written in shorthand, /16. The default subnet mask for Class A networks is 255.0.0.0, or written in shorthand, /8, and for Class C it is 255.255.255.0, or written in shorthand, /24. 255.255.255.255 is an IPv4 broadcast address. As a subnet mask it is represented as /32 (in shorthand) in the classless interdomain routing (CIDR) notation.
Which TCP/IP protocol uses port 445?
A) FTP
B) SSH
C) SMB
D) SNMP
C. Server Message Block (SMB) is a protocol used to provide shared access to files, printers, and other network resources. It originally ran on NetBIOS over UDP using ports 137/138 and over TCP using ports 137 and 139, but it’s now part of the TCP/IP stack and uses port 445. Running on NetBIOS allows SMB to facilitate file sharing on a single network, while being part of TCP/IP allows it to facilitate file sharing across the Internet. By itself, SMB is not secure, so it needs other network appliances or software to secure the data being sent over its port(s). File
Transfer Protocol (FTP) uses ports 20/21,
Secure Shell (SSH) uses port 22, and
Simple Network Management Protocol (SNMP) uses ports 161/162.
What rendition of SMB was used by Windows servers and NAS servers but is no longer often used?
A) CIFS
B) Samba
C) NFS
D) SMB3
A. All of the answer choices are communications protocols for sharing resources. The Common Internet File System (CIFS) is Microsoft’s version of Server Message Block (SMB.) Once upon a time CIFS was used extensively for file sharing over a network, but it has since fallen out of favor. While CIFS and SMB both facilitate file sharing, SMB does it better and has other features as well. Samba and Network File System (NFS) facilitate sharing files between clients and servers in Linux distributions. Samba will allow mixed environments with both Windows and Linux machines to share files. NFS will not.
For IPv6, which of the following statements are true? (Choose two.)
A) Each IPv6 interface can have only one address.
B) Each IPv6 interface is required to have a link-local address.
C) IPv6 addresses are incompatible with IPv4 networks.
D) IPv6 does not use broadcasts.
B, D. Each IPv6 interface can and often does have multiple addresses assigned to it. IPv6 is backward compatible with IPv4 by using tunneling, dual stack, or translation. IPv6 uses multicast addresses in place of broadcast addresses, and a link-local address is established either automatically when a computer boots up or by manually configuring it, but either way the link-local address must be present.
Which network connectivity device is seldom used in modern networks, except to extend a network?
A) Bridge
B) Hub
C) Switch
D) Router
B. Hubs were once used extensively in Ethernet networks, but they have fallen out of favor because they have a large disadvantage when compared to switches. A hub forms a single collision domain with all of their ports. On a switch, each port is its own collision domain. A switch keeps a table of its ports and the media access control (MAC) address that can be reached from each port. A switch will only forward a packet to a specific port, whereas a hub will forward a packet to all of its ports. The exception is that a broadcast packet will be sent to all switch ports. Switches are faster and more accurate than hubs and are used almost exclusively as the connectivity device within a local area network (LAN.)
There is a TCP/IP protocol that should only be used locally because it has virtually no security. It may be used as a part of a preboot execution environment (PXE) or with thin clients booting from a network drive. It uses very little memory and is good for transferring boot files or configuration data between computers on a LAN, and it is connectionless. Which file transfer protocol is this?
A) FTP
B) TFTP
C) FTPS
D) SMTP
B. The Trivial File Transfer Protocol (TFTP) is a very simple connectionless protocol. It has little overhead, meaning that it doesn’t take much memory to run it. This makes it perfect for booting a thin client across a network. It can be used to transfer the needed boot files to devices that don’t have hard drives. It should not be used to transfer files across the Internet because it is not secure. File Transfer Protocol (FTP) is more robust than TFTP. File Transfer Protocol Secure (FTPS) is a secure version of FTP. Simple Mail Transfer Protocol (SMTP) is used to send email messages.
Which of the following IPv6 addresses is equivalent to 127.0.0.1 in IPv4?
A) ::0
B) ::1
C) ::127
D) 2000::/3
B. 127.0.0.1 is the IPv4 loopback address, used to ping the local network interface. The IPv6 equivalent is ::1.
Which networking device has multiple ports, each of which is its own collision domain, and examines the header of the incoming packet to determine which port the packet gets sent to?
A) Hub
B) Switch
C) Bridge
D) Router
B. Switches provide centralized connectivity for a LAN. Switches examine the header of incoming packets and forward each to only the port whose associated media access control (MAC) address matches the receiving MAC address in the header. Hubs are seldom used now because the entire hub is one collision domain and when a packet is received, the hub sends the packet out to all of its ports indiscriminately. Bridges are used to connect different networks to work as one, and routers are used to forward packets from one network to other networks.
A technician is going to set up a Wi-Fi network using standard omnidirectional antennae. Because of the building configuration, transmitting signals for the greatest distance is the technician’s primary criterion. Which standard should they choose?
A) 802.11a
B) 802.11g
C) 802.11n
D) 802.11ac
C. Of the Wi-Fi standards listed, 802.11n has the longest range by default, at roughly 70 meters indoors and 250 meters outdoors. 802.11ac is newer and faster than 802.11n, but it transmits exclusively in the 5 GHz range, which restricts its functional distance. 802.11a, which is legacy and uses the 5 GHz frequency range, could only send a signal about 30 meters, and 802.11g, which is also legacy but uses the 2.4 GHz frequency range, could only send a signal about 50 meters.
What marks the boundary of a IPv4 broadcast domain?
A) Hub
B) Switch
C) Router
D) Modem
C. Hubs send every communication they receive out every connected port. Switches will send broadcast packets out every port, but otherwise will send packets to a specific port based on the MAC address. A router will not forward any broadcast packet; therefore a router is the boundary of an IPv4 broadcast domain. A modem (modulator/demodulator) converts signals from one type to another, such as from an analog signal to a digital one.
You have been asked to install a Wi-Fi network in a building that is approximately 100 meters long and 25 meters wide. Because of cost considerations, you will be using 802.11ac. At a minimum, how many wireless access points will you need?
A) Two
B) Three
C) Four
D) Six
B. The 802.11ac standard has an indoor range of approximately 35 meters. At a minimum, you will need three access points. Depending on coverage and indoor interference, such as thick walls, you might need more.
If you are connecting to a website that encrypts its connection using TLS, what port does that traffic travel on?
A) 21
B) 80
C) 143
D) 443
D. To encrypt traffic between a web server and client securely, Hypertext Transfer Protocol Secure (HTTPS) can be used. HTTPS connections are secured using either Secure Sockets Layer (SSL) or Transport Layer Security (TLS). HTTPS uses port 443. Port 21 is used by File Transfer Protocol (FTP), port 80 is used by Hypertext Transfer Protocol (HTTP), and port 143 is used by Internet Mail Access Protocol (IMAP).
What type of network spans multiple buildings or offices, possibly even crossing roads, but is confined to a relatively small geographical area?
A) LAN
B) WAN
C) PAN
D) MAN
D. Networks that are larger than a LAN but confined to a relatively small geographical area are metropolitan area networks (MANs). A MAN is generally defined as a network that spans a city or a large campus. LAN stands for local area network. PAN (personal area network) is the smallest of the types of networks, and a WAN is the largest type of network. It could connect faraway cities or even other countries.
Which of the following shorthand notations corresponds to the CIDR subnet mask 255.255.224.0?
A) /19
B) /20
C) /21
D) /22
A. A subnet mask of 255.255.224.0 has 8 bits in each of the first 2 octets set to on, and it has 3 bits in the third octet on. Therefore, it corresponds to /19 in shorthand. In the binary number system (base two), each bit has two possible values, 0 or 1. Each bit in an octet going from right to left increments by an exponent of two, making the bits of the octets worth the decimal values as follows: | 128 |64 |32 |16 | 8 | 4 | 2 | 1 |. Bits for the subnet mask are always used from left to right, so one bit would be equal to a decimal value of 128. Two bits would be equal to a decimal value of 192 (128 + 64). Three bits would be equal to a decimal value of 224 (128 + 64 + 32), and so on. When all 8 bits of the octet are used for the subnet mask, the equivalent decimal value is 255. For this example, the first 2 octets (8 bits each) are completely on, and in the third octet, only 3 bits are on, making a total of 19 bits in the subnet mask turned on to indicate the network number (8 + 8 + 3 = 19).
You are configuring hosts on a network running IPv4. Which elements are required for the computer to connect to the network?
A) IP address
B) IP address and subnet mask
C) IP address, subnet mask, and default gateway
D) IP address, subnet mask, default gateway, and DNS server address
B. To communicate on an IPv4 network, a host must be configured with a valid IP address and a subnet mask. A default gateway is needed only if the host will connect to a remote network. DNS servers are optional but useful, because they resolve hostnames to IP addresses.
You work at a tech support company and a customer called reporting that they received an error, something about a duplicate IP address. Why are they getting this message? (Choose two.)
A) All hosts on a network must have a unique IP address.
B) A PC is manually configured with an IP that is in the DHCP scope.
C) A PC is manually configured with an IP that is not in the DHCP scope.
D) None of the PCs have been manually configured.
A, B. No two nodes on any network, whether IPv4 or IPv6, can have the same IP address because the host portion (or interface ID) of the IP address is what identifies the individual computer on the network. If the network has some machines manually configured, which is generally done with servers, and the remainder of the computers are configured to use Dynamic Host Configuration Protocol (DHCP), you would need to ensure that the manually configured numbers are outside of the DHCP scope (the numbers the DHCP server will automatically assign) but within the bounds of the network. For example, in an IPv4 network, if the network number is 200.100.1.0, the router, which is also acting as a default gateway, might be assigned 200.100.1.1, and numbers from 200.100.1.2 through 200.100.1.20 could be reserved for static configuration on devices that need an IP address that does not change. The DHCP scope would need to not include those numbers. If the network needed an available 180 IP addresses, then 200.100.1.21 to 200.100.1.200 could be safely assigned to the DHCP scope, avoiding any IP address duplication.
Which obsolete Wi-Fi encryption standard uses a static key, which is commonly 10, 26, or 58 characters long?
A) WPA3
B) WPA2
C) TKIP
D) WEP
D. Wired Equivalent Privacy (WEP) was one of the first security standards for wireless devices. It uses a static key; the keys are commonly 10, 26, or 58 hexadecimal characters long. WEP was depreciated in 2004 because it was no longer secure and was replaced temporarily by WPA, which was quickly replaced by WPA2. WPA3 is the current and most secure standard.
