Chapter2 Flashcards

Question

``` Which of the following tools do cable installers use to connect bulk cable runs to wall plates and patch panels? A crimper A splicer A pigtail A punchdown block tool ```

Answer 1

D. Installers use a punchdown block tool to connect the ends of bulk cable runs to jacks in wall plates and patch panels. A crimper or crimping tool is a jawed device that enables installers to squeeze the two halves of an RJ45 or RJ11 connector together, securing the connector to the cable. Installers use a splicing tool to splice two cable segments together. There is no tool called a pigtail.

Answer 2

A. Multimode fiber-optic cable best meets the client’s needs. Fiber-optic cable supports the required 1000 Mbps data rate and can connect networks that are more than 1,000 feet apart. Fiber-optic cable is immune to EMI. Although both multimode and single-mode fiber would meet the corporation’s general needs, multimode is best in this scenario because it is less expensive than single-mode fiber. Twisted pair wiring (STP or UTP) meets the data rate and cost requirements but does not support connections longer than 100 meters. Thin coaxial cable does not support the data rate or distances longer than 185 meters.

Answer 3

A, B, and C. BNC connectors are used for coaxial Thin Ethernet networks, and N-type connectors with Thick Ethernet. F-type connectors are used for coaxial cable television installations. Straight tip (ST) connectors are used with fiber-optic cable, and RJ11 connectors are used for telephone installations.

Answer 4

C. Either CAT6 or CAT6a UTP cable will provide the currently required 1 Gbps data rate, with a migration path to 10 Gbps in the future. The backbone cabling connecting the two LANs needs to be fiber optic, since it exceeds the distance limitations of twisted pair and coaxial cable. CAT5 cable conceivably runs at 1 Gbps; however, it does not run at 10 Gbps.

Answer 5

D. The Thin Ethernet LAN is the network most endangered by the cable break. If a bus network is severed, all of the workstations on it are affected because the cable segments are no longer terminated at one end. The Gigabit Ethernet network uses a star topology, which means that only the one computer using the severed cable could be disconnected from the network. An FDDI double ring network can survive a single cable break without any workstations being affected.

Answer 6

A. You use a punchdown block tool to connect the ends of bulk cable runs to jacks in wall plates and patch panels. The steps of the process are as follows: Strip some of the insulating sheath off the cable end to expose the wires. Separate the twisted wire pairs at the ends. Strip a small amount of insulation off each wire. Insert the wires into the appropriate contacts in the jack. Press the bare wire down between the two metal contacts that hold it in place. Cut off the excess wire that protrudes past the contacts. You must repeat the process of punching down for both ends of your internal cable runs.

Answer 7

D. ST, SC, fiber LC, and MTRJ are all connectors used with fiber-optic cables. F-type connectors are used with coaxial cables.

Answer 8

D and E. Category 6a (CAT6a) twisted pair cable is a variant on CAT6 that enables you to create 10GBase-T networks with segments up to 100 meters long. Category 7 (CAT7) cable adds shielding both to the individual wire pairs and to the entire cable, for even greater resistance to crosstalk and noise. CAT7 supports 100-meter 10GBase-T segments as well. CAT5 and CAT5e are not suitable for use with 10GBase-T. You can use CAT6 for 10GBase-T, but it is limited to 55-meter segments.

Answer 9

C and D. The DB-9 and DB-25 connectors were at one time ubiquitous on personal computers, providing peripheral connections to modems, printers, and other devices. They have since been largely eliminated in favor of USB. BNC connectors were used for Thin Ethernet networking, but they have been replaced by unshielded twisted pair (UTP) cable with RJ45 connectors. RJ11 connectors are used for telephone connections.

Answer 10

A. CAT3 cable was originally intended for use in voice-grade telephone networks but was later certified for use in data networks. CAT3 cable can support data transfer rates from 4 Mbps up to 100 Mbps (using the now-deprecated 100Base-T4 and 100VG-AnyLAN standards). Although this type of cable could run at 100 Mbps, it was seldom used at speeds greater than 10 Mbps. CAT5 cable was the primary replacement for CAT3, supporting data rates up to 100 Mbps. CAT5e and CAT6 are rated for data rates up to 1 Gbps, as on Gigabit Ethernet networks. CAT6 can even support 10 Gbps transfer rates over shorter distances.

Answer 11

E. Because the company has few employees, they are in a single location, and the client is concerned with minimizing the cost, the best solution is to use a star topology with prefabricated twisted pair cabling and an external installation method. The star topology uses a central switch. Ed can use two switches, one in each room, to connect computers to the network. Prefabricated twisted pair cabling, which has the connectors already attached and is available in specific lengths, will keep the cost to a minimum. Since the employees are all located in the same building, with a common wall and door and a drop ceiling, the external installation method is the best choice. It is not possible to use a bus topology or coaxial cable for Gigabit Ethernet. Ed could conceivably use fiber-optic cable in a star topology for Gigabit Ethernet, but it is more difficult to install and very expensive. An internal installation, which uses a combination of bulk cable with no connectors and prefabricated cables, is more expensive than an external installation and is typically used for larger networks.

Answer 12

B and D. The main cable types used in LANs today are multimode fiber optic and unshielded twisted pair. Single-mode fiber optic is used primarily for long-distance wide area network (WAN) connections, and coaxial cable is no longer used for LANs.

Answer 13

B, D, and F. Coaxial cable has two conductors within the same sheath that share a common axis. These conductors are surrounded by an outer insulating sheath of either PVC or Teflon. Copper cables carry electrical signals. Only fiber-optic cables carry light pulse signals.

Answer 14

F. All twisted pair Gigabit Ethernet implementations require all four wire pairs to achieve 1000 Mbps transfer rates.

Answer 15

B, C, and D. CAT5 cable was the original cable standard intended for transfer rates up to 100 Mbps. CAT5e and CAT6 support 100 Mbps and are also rated for data rates up to 1000 Mbps. All three of these standards also support the 10 Mbps transfer rate. CAT3 can support both 10 and 100 Mbps, but it requires four pairs for 100 Mbps.

Answer 16

A, B, D, E, and F. Fiber-optic cable comes in two types: multimode and single-mode. Fiber-optic cables vary in light source (LED or laser), cable grade (glass or plastic), and size of the core conductor. Single-mode uses a higher-grade glass conductor with a laser light source. Multimode fiber uses an LED light source. Both types can use either ST or SC connectors to physically connect end devices to a fiber-optic network. Fiber-optic cable is used to extend networks over long distances. Fiber-optic cables do not use IDC connectors, which are intended for use with shielded twisted pair (STP) cable.

Answer 17

A, D, and F. The use of bulk cable with no connectors, wall plates, and rack-mounted patch panels are all characteristics of an internal wiring installation. Internal installations typically cover large geographic areas that require cabling through walls, ceilings, and around other obstacles, making the cabling difficult to move. Solid core wiring is used for longer cable runs, whereas shorter cable runs such as connections from node to wall plate use prefabricated stranded core cables with connectors attached.

Answer 18

E. Ralph should use a mesh topology with redundant fiber-optic cable runs and an internal installation method. This will meet the requirements for connecting the LANs and for providing redundancy and fault tolerance. Fiber-optic cable is immune to electromagnetic interference (EMI) and can span long distances. The internal installation method is most often used in larger networks, where end systems are geographically distant, such as different buildings and floors. The star topology will not fulfill the requirements of this backbone network since it provides no redundancy. Twisted pair cable can’t span distances more than 100 meters, and it is highly susceptible to EMI. Coaxial cable can’t span distances more than 500 meters, and it is also susceptible to EMI. The bus topology cannot use twisted pair cabling and doesn’t support cable runs longer than 500 meters.

Answer 19

B. Although the design calls for an archaic technology, a Thin Ethernet network runs at 10 Mbps and can support 20 workstations over a maximum distance of 185 meters, thus achieving the primary goal. However, Thin Ethernet uses copper-based coaxial cable, which is susceptible to EMI, and it uses a bus topology, which is not tolerant of a cable break. Therefore, the solution doesn’t achieve either of the secondary goals.

Answer 20

D. Fiber-optic cable, in a Gigabit Ethernet installation, is not more tolerant of cable breaks than UTP. Some fiber-optic networks include fault tolerance, but Ethernet does not. Each UTP cable connecting a computer to a switch can be no longer than 100 meters, making 200 meters the maximum distance between two computers on a UTP network. Connecting two buildings with a copper-based cable creates an electrical connection between them, which can be hazardous. Fiber-optic cable does not create an electrical connection. Fiber-optic cable is also unaffected by the EMI generated by manufacturing equipment.

Answer 21

A. FLP signals are an enhancement of the normal link pulse (NLP) signals defined in the 10Base-T standard, which verify the integrity of the link. In 100Base-T, the FLP signals retain that function, but they also enable multispeed devices to negotiate the speed at which they will operate. FLP signals do not indicate collisions or bad frames.

Answer 22

B. The 10GBase-CX4 specification calls for the use of a twinaxial copper cable with segments no longer than 20 meters. The 10GBase-LR, 10GBase-ER, 10GBase-LX4, and 10GBase-SR specifications all call for fiber-optic cable.

Answer 23

D. The multispeed network interface adapters in the computers can run at 1 Gbps speed using the existing CAT5 cable, but the 100Base-T switch must be replaced with a 1000Base-T switch. While the network might run better with a cable upgrade, it is not immediately necessary. Replacing the network interface adapters is not necessary because the existing multispeed adapters can run at 1 Gbps if they are connected to a 1000Base-T switch.

Answer 24

C. 1000Base-T is fastest Ethernet specification that can run on CAT5 UTP cable. 10GBase-T requires Category 5e (CAT5e) or Category 6 (CAT6) UTP cable. 100Base-TX can use CAT5 cable, but it runs at one-tenth the speed of 1000Base-T. 1000Base-LX is a fiber-optic specification that cannot run on CAT5 UTP or any copper cable.

Answer 25

B, C, and E. The three IEEE 10 Mbps standards for Ethernet are 10Base2, 10Base5, and 10Base-T. 10Base2 is limited to 185-meter segments; 10Base5 is limited to 500-meter segments; and 10Base-T is limited to 100-meter segments. The other options are not valid.

Answer 26

A and D. The first version of DIX Ethernet (Version 1) supported RG-8 Thick coaxial cable in a bus topology. Version 2 added support for Thin coaxial cable (RG-58) but was still limited to a bus topology. RG-10 and RG-14 are not Ethernet cable types.

Answer 27

D. The best solution in this scenario is to upgrade to 1000Base-T and replace the existing hubs with switches. 1000Base-T provides the fastest transfer speeds supported by the existing cable. Since users are complaining that the network is slow with the existing hubs, it makes sense to replace the shared hub environment with switches that offer dedicated bandwidth out each port. Any solution that does not replace the hubs would not address the users’ complaints. 100Base-TX would provide a speed increase, but it runs at one-tenth the speed of 1000Base-TX. Upgrading to 100Base-FX would require the cabling to be replaced with fiber optic, which would be very expensive.

Answer 28

C. In this situation, the best choice is to replace the hubs with switches, since the network is relatively small and cost is an issue. In addition, all users must be able to share information directly with one another and to access the servers. On the existing network, all users share the same 100 Mbps communication channel, and each computer must take turns transmitting. By replacing the hubs with switches, you provide each computer with a dedicated 100 Mbps connection to the switch, while reducing unnecessary traffic and collisions on the network. There is no such thing as a dedicated hub. Splitting the network into two routed LANs with 20 users each is not the best solution, since all users must share information on a constant basis. Also, cost is a factor and routers are more expensive than switches. Replacing the hubs with a layer 3 switch and defining two VLANs with 20 users each is not a reasonable solution because layer 3 switches are very expensive. Layer 3 switches and VLANs are typically used in larger enterprise networks.

Answer 29

B. A bridge can split a single network into two collision domains, because it forwards only the packets that are destined for the other side of the bridge. The bridge forwards all broadcast packets, so it maintains a single broadcast domain. A hub maintains a single collision domain and a single broadcast domain. A switch creates a separate collision domain for each port, and a single broadcast domain for the entire network. A router creates two collision domains, but it does not forward broadcasts, so there are two broadcast domains as well.

Answer 30

C. VLANs are data link layer local area networks (LANs) defined within switches. Only devices (and users) connected to ports belonging to the same VLAN can communicate with each other until a layer 3 device, such as a router or a layer 3 switch, is added to the network. Re-creating and reconfiguring the VLANs will not correct this problem. Traffic filters are usually implemented on routers. VLANs do not have to use the same data link protocol.

Answer 31

C. Broadband routers generally do not function as proxy servers, which are application layer devices used to regulate access to the Internet. Many broadband routers are also wireless access points, enabling users to construct a LAN without a complicated and expensive cable installation. Many broadband routers have switched ports for connections to wired devices, such as printers and computers. Most broadband routers use DHCP to assign IP addresses to devices on the private network.

Answer 32

C. A modulator/demodulator is any device that converts analog signals to digital signals and digital signals back to analog signals. The digital device does not have to be a computer, and the analog device does not have to be the PSTN. There are many devices that are incorrectly referred to as modems, such as devices that connect a digital LAN to a digital WAN or all-digital devices that connect computers to the Internet.

Answer 33

C. Replacing routers with switches turns an internetwork into a single large subnet, and VLANs exist as logical elements on top of the switching fabric. Although VLANs are the functional equivalent of network layer subnets, the systems in a single VLAN are still connected by switches, not routers. Bridges connect network segments at the data link layer and selectively forward traffic between the segments. However, bridges do not provide a dedicated connection between two systems like a switch does, and they do not make it possible to convert a large routed internetwork into a single switched network. Therefore, they have no role in implementing VLANs. Hubs are physical layer devices that propagate all incoming traffic out through all of their ports. Replacing the routers on an internetwork with hubs would create a single shared network with huge amounts of traffic and collisions. Hubs, therefore, do not connect the computers in a VLAN.

Answer 34

A. A firewall is a filter that can prevent dangerous traffic originating on one network from passing through to another network. A device that connects two networks together and forwards traffic between them is a router, not a firewall. A device that enables Internet network clients with private IP addresses to access the Internet is a description of a NAT router or a proxy server, not a firewall. A device that caches Internet data is a proxy server or caching engine, not a firewall.

Answer 35

B. Service-dependent filtering blocks traffic based on the port numbers specified in the transport layer header fields. Because port numbers represent specific applications, you can use them to prevent traffic generated by these applications from reaching a network. IP address filtering operates at the network layer. Deep packet inspection (DPI) scans the contents of packets, rather than their headers. Next generation firewall (NGFW) defines a device with advanced protection capabilities; port number scanning is a basic firewall function.

Answer 36

A. A repeater is a physical layer device that regenerates incoming signals and retransmits them. A hub is a type of repeater that receives data through any one of its multiple ports and retransmits the data out through all of its other ports. Bridges and switches are data link layer devices, and routers are network layer devices. None of these three can be described as multiport repeaters.

Answer 37

C. Source route bridging was a technique used on Token Ring (and not Ethernet) networks, in which a Routing Information Field (RIF) in the packet header identified the network segments the packet should follow to reach its destination. Store and forward, transparent, and multiport bridges have all been used on Ethernet networks.

Answer 38

C and D. Most operating systems are capable of functioning as routers or firewalls. To route traffic, the system must have two network connections. A software firewall can be part of a computer’s routing functionality, or it can be a stand-alone firewall that protects only the local system. Computers cannot function as hubs or switches because multiple ports would be required and standard network adapters don’t implement those functions.

Answer 39

D. Service-dependent filtering blocks traffic based on the port numbers specified in the transport layer header fields. Because port numbers represent specific applications, you can use them to prevent traffic generated by these applications from reaching a network. IP address filtering enables you to limit network access to specific computers; it is not service dependent. Filtering based on hardware addresses provides the same basic functionality as IP address filtering, but it is more difficult to spoof hardware addresses than IP addresses. Filtering by protocol identifier enables you to block all traffic using TCP or UDP; it is not service dependent.

Answer 40

C. A personal firewall is an inexpensive way to protect an individual computer from Internet incursions. Three copies of the product are much less expensive than any of the other suggested solutions. Installing a hardware firewall is a complex and expensive solution, not suitable for a small network. An IPS is a relatively expensive solution, suitable for larger networks. An IDS is a relatively expensive solution, and connecting it to a switched port would not enable it to protect the other computers on the network. A port scanner is a device that performs scans on demand. It does not continuously monitor ports, and it does nothing to protect them.

Answer 41

B and C. Hubs operate at the physical layer and switches at the data link layer. Hubs and switches both create a single broadcast domain for all of the connected devices. Switches create a separate collision domain for each connected device, whereas hubs create a single-collision domain. There are switches (but not hubs) with network layer (layer 3) functionality.

Answer 42

A and C. STP disables redundant links between switches that can allow packets to circulate endlessly around the network. This is called a bridging loop. As a result of a bridging loop, the network can be flooded with broadcast traffic, which is called a broadcast storm. STP does nothing to prevent late collisions, which is an Ethernet timing problem, or crosstalk, which is a cabling fault.

Answer 43

B and C. A switch is essentially a multiport bridge. Both switches and bridges process incoming packets by scanning their data link layer hardware addresses and forwarding the packets out the port connected to the destination system. The primary difference between them is that switches have many ports, whereas bridges have only two. Hubs and routers are physical layer and network layer devices, respectively, and perform different functions.

Answer 44

A and D. Servers that must be accessible to clients on the Internet, such as web and email servers, are typically isolated from the internal network by one firewall and from the Internet by a second firewall. The area where these servers reside is often called a perimeter network, or a demilitarized zone (DMZ). It is not called a peripheral network or a Berlin wall.

Answer 45

A. Cut-through switches are fast because they look at only the first six bytes (the destination media access control, or MAC, address) when forwarding a frame. They do not perform a cyclical redundancy check (CRC) on the entire frame’s contents prior to forwarding it out a port leading to the destination. Source route is a bridging technique in which the source host, not the switch, determines the path a frame will take through a network to reach a destination. Store-and-forward switches take in the entire frame and verify its contents by performing a CRC calculation before forwarding it. There is no switch called a destination switch.

Answer 46

D. STP operates at the data link layer of the OSI model, so it works with hardware addresses, not IP addresses. Switches use STP to prevent redundant links from causing traffic loops on the network.

Answer 47

B. The process by which STP populates its database with information about each port in a switch and designates the ports as forwarding or blocking is called convergence.

Answer 48

C and D. Home and small office networks typically consist of a single subnet and require only a basic switch without the advanced virtual LAN capabilities that enable administrators to create separate subnets. Most home and small office networks have a DHCP server that assigns IP addresses and other TCP/IP configuration settings to clients. The DHCP server can be integrated into a broadband router or another Internet access sharing solution. Most home and small office networks support network address translation, enabling them to use private IP addresses and still access the Internet. 10GBase-T is the designation for UTP-based 10 Gigabit Ethernet, which is an advanced standard for network interface adapters often found in servers.

Answer 49

A. A firewall that supports stateful packet inspection examines other network and transport layer header fields, looking for patterns that indicate damaging behaviors, such as IP spoofing, SYN floods, and teardrop attacks. Port number filtering is the most commonly used form of packet filtering; it is not the same as stateful packet inspection. Blocking traffic based on IP addresses prevents specific systems from accessing a network; stateful packet inspection is a much more complicated operation. Packet filtering based on protocol identifiers enables you to block TCP traffic; this is not stateful packet inspection.

Answer 50

B. Bridges are data link layer (layer 2) devices. Routing is a network layer (layer 3) function, so it is not a type of bridge. A store-and-forward, or simple, bridge examines each packet and decides whether to forward it to the connected network. A transparent bridge compiles a database of forwarding information, based on the packets it has processed previously. A multiport bridge provides connections to multiple networks; a switch is a type of multiport bridge.

Answer 51

B. Connecting subnets with routers at the network layer maintains the data link layer administrative boundaries that prevent broadcast transmissions from being propagated throughout the entire internetwork. Switching eliminates those data link layer boundaries, and administrators can use VLANs to simulate them. Because hubs propagate all of the traffic they receive out through all of their ports indiscriminately, they create no administrative boundaries. Firewalls are filtering devices that protect networks against malicious traffic. Their functions are not related to VLANs. Switches are essentially multiport bridges that forward incoming traffic only to the device for which it is destined. Therefore, bridges are more closely related to eliminating administrative boundaries than to establishing them.

Answer 52

D. A simple media converter is a physical layer device that can connect different types of network media together, as long as they have the same speed and duplex settings. Because the converter simply retransmits the signals, the single-collision domain is maintained. Bridges and switches are data link layer devices that create multiple-collision domains. Routers are network layer devices that create separate collision and broadcast domains.

Answer 53

A. Wireless range extenders are physical layer devices that receive signals from wireless access points and network adapters and retransmit them, enabling devices to connect that are farther apart than the network would normally support. Because the extenders do not process the packets in any way, but just retransmit the signals, they do not operate at any layer above the physical.

Answer 54

B. A switch is a data link layer device that essentially performs the function of a bridge for each device connected to one of its ports. It can therefore be described as a multiport bridge. Routers, hubs, and gateways are devices that operate at the network, physical, and application layers, respectively, so they cannot be described as bridges.

Answer 55

D. A gateway enables two devices using different protocols to communicate by performing translation and conversion services for them. Routers, hubs, and switches all require the same protocol at some of the OSI model layers.

Answer 56

A. Each port on a router defines a separate collision domain. Hubs forward all traffic to all of the connected nodes, so each network segment is a single-collision domain. Routers do not forward broadcasts, so each network segment is also a separate broadcast domain.

Answer 57

A, B, and D. Routers are network layer devices that do not forward broadcast messages, so they create separate broadcast domains for each network. Switches do forward broadcasts, forming a single broadcast domain. Routers and switches can communicate using dedicated protocols. As data link layer devices, switches read only hardware addresses from packet frames; routers forward traffic based on the IP addresses in packets’ IP headers.

Answer 58

A. Media converters will enable Ralph to join the multimode fiber-optic run to the UTP at both sides of the courtyard while maintaining a single network at minimum cost. Inexpensive small business hubs and switches cannot join different media together. Routers can join different media, but they are more expensive, and they would separate the installation into three separate networks.

Answer 59

A. All half-duplex port connections on a store-and-forward switch represent a different collision domain. Full-duplex connections aren’t subject to collisions, so they do not define separate collision domains.

Answer 60

A. If the fifth computer is in a different VLAN from the other four, it would be unable to communicate with them. A switching loop would affect communication between all of the computers, not just the fifth one. An MTU black hole is a condition in which a system is unable to complete the Path MTU Discovery process, due to an intervening firewall. Because these five computers are all on the same LAN, they all have the same MTU, and Path MTU Discovery is not necessary. A virtual router would enable switched computers on different subnets to communicate with each other; it would not prevent them from communicating.

Answer 61

A. Hubs are network devices that simply receive signals through one port, electrically enhance them, and transmit them out through another port. Routers, switches, and bridges are capable of reading the signals and processing them, which classifies them as intelligent.

Answer 62

B and D. The computers in a single VLAN can be located anywhere on a switched network, regardless of the physical configuration of the switches. A broadcast message generated by a computer in a VLAN is transmitted to all of the other computers in that VLAN only, just as if the systems were physically located on a separate LAN or subnet. Unicast transmissions between computers on a switched network do not require VLANs because the switches create what amounts to a direct connection between the two systems. VLANs are needed only for communication processes that require using broadcasts, which, if transmitted without VLANs, would flood the network. Even though they are a purely logical construction, VLANs function just like physical subnets and require routers for communication between them. Routers are often integrated into layer 3 switches to enable communication between VLANs.

Answer 63

A and B. Adding a router splits the Ethernet LAN into two LANs, creating two separate broadcast domains. Each computer, therefore, has a smaller number of broadcast messages to process. Because the network is split by the router, the amount of unicast traffic on each subnet is reduced.

Answer 64

B. Standard hub ports have a crossover circuit, which ensures that the transmit signals at one end of the connection arrive at the receive pins at the other end. The uplink port in a hub bypasses the crossover circuit so that two connected hubs do not have crossover circuits that cancel each other out. A connection between a standard port and an uplink port, using a standard cable, results in a single crossover, which is correct wiring. Each of the other solutions results in either two crossovers or no crossovers, which is incorrect.

Answer 65

D and E. By default, a switched LAN consists of a single broadcast domain. To create multiple broadcast domains, you can install routers to split the installation into two or more networks, because routers do not forward broadcasts. The other possibility is to create virtual LANs (VLANs) in the switches. Each VLAN is a separate broadcast domain. All of the other options would have no effect on the number of broadcast domains on the network.

Answer 66

B. Bridges and switches are data link layer devices that forward frames based on the destination MAC address contained in the frame. They operate in promiscuous mode, listening and processing all frames on each segment, and they build forwarding tables with this information. Forwarding tables are built based on source MAC addresses. Bridges are protocol independent; they are not involved with the upper layer protocols being carried on the LAN. Broadcast domains are defined by network layer devices, not data link layer devices.

Answer 67

A and D. Every network device has unique hardware addresses coded into the network interface adapter, and administrators can use these addresses to select the devices that will be part of a specific VLAN. IP addresses are layer 3 constructs and are not used to configure VLANs, which operate at layer 2. When VLANs are implemented inside the switch, selecting the ports to which specific computers are attached is a simple way to identify the computers in a particular VLAN. Although DNS names do uniquely identify computers on a network, DNS is an application layer process and has nothing to do with the switching and routing processes, which occur at the data link and network layers. Therefore, you cannot use DNS names to identify the computers in a VLAN.

Answer 68

C. A switch is best described as a multiport bridge because it reads the hardware addresses of incoming packets and forwards them out through the port for the destination node. Although a switch does function at layer 2 of the OSI model (the data link layer), it is not a router, which connects networks together at layer 3 (the network layer). Hubs and repeaters are physical layer (layer 1) devices that are not capable of performing the functions of a switch.

Answer 69

C. The main reason why switches improve the efficiency of an Ethernet LAN is that they create a separate collision domain for each switched port, eliminating most collisions. Collisions result in packets having to be retransmitted, so fewer collisions means fewer retransmissions, which improves performance. Switches do not forward packets faster than hubs. Switches do forward broadcast transmissions. Switches do read hardware addresses, not IP addresses.

Answer 70

D. A collision domain is a LAN with a shared network medium, so that two devices transmitting at the same time generate a signal quality error, also known as a collision. Ethernet LANs connected by hubs create a shared medium, whereas switched networks create a separate collision domain for each connected node. Routers create separate collision domains. A group of computers able to receive broadcasts is the definition of a broadcast domain, not a collision domain. Overlong cables can precipitate collisions but do not define a collision domain.

Answer 71

A and C. VoIP uses the terms terminal and endpoint to refer to the device with which users make calls, including computers and telephone handsets. A VoIP gateway is the device that provides the conduit between an IP network and the Public Switched Telephone Network (PSTN). A VoIP private branch exchange (PBX) is a device that switches calls between endpoints on the local IP network and provides access to external Internet lines.

Answer 72

A. Hubs (or concentrators) are physical layer devices that amplify and repeat signals out all ports except the one through which the data was received, regardless of the destination. Hubs are used to physically connect end systems to a star topology. Hubs typically provide an internal crossover circuit connection. Uplink ports are used to extend the distance of a star network, forming a hierarchical star.

Answer 73

A, D, and E. Routers are network layer devices that use IP addresses to forward frames, not MAC addresses. Routers are protocol dependent. They must support the network layer protocol being routed. As a network layer device, a router defines networks (or LANs) that represent a separate broadcast domain. Routers do not build their routing tables or forward frames using MAC addresses.

Answer 74

A and B. The 100Base-TX specification specifies two hub types: Class I and II. Class I hubs perform signal translation; Class II hubs do not. A network can have only one Class I hub per collision domain; a network can have two Class II hubs per collision domain. The other options do not exist.

Answer 75

C. Routers store and maintain route information in a routing table that is stored in memory, not in a local text file. All of the other statements about routers are true.

Answer 76

D. The firewall is a conduit between the private network and the ISP’s network (which provides access to the Internet), through which all traffic must pass. This ensures that the firewall has the opportunity to examine every packet that passes between the private network and the Internet and filter out those that are not authorized. If the firewall was located in the midst of the private internetwork, it would be possible for Internet computers to bypass the firewall and communicate directly with the private systems. Placing the firewall on the far side of the router would put it on the ISP’s network, causing it to filter all of the ISP’s traffic and not just that destined for the private network. Installing the firewall at the ISP’s site would have the same effect as installing it on the far side of the router at the private network site.

Answer 77

A and B. The FTP protocol uses two well-known ports, 20 and 21. A firewall must have both of these ports open to admit FTP traffic. FTP does not require ports 22, 23, or 24.

Answer 78

D. A proxy server is an application layer service because it receives Internet service requests from client computers, reads the application layer protocol data in each request, and then generates its own request for the same service and transmits it to the Internet server the client specifies. Only an application layer service can read and process the application layer data in network packets. A proxy server cannot be a data link layer device because it can provide Internet access to an entire internetwork, while the data link layer is concerned with communications on a single subnet. Proxy servers cannot be network layer devices because the network layer handles all internetwork packets indiscriminately and is unaware of what application generated the data carried inside the packets. The transport layer is not involved in processing application data, so proxy servers cannot be said to function at the transport layer.

Answer 79

A. A Remote Authentication Dial-In User Service (RADIUS) server can provide authentication, authorization, and accounting services for remote access servers. Intrusion detection systems (IDSs), Next Generation Firewalls (NGFWs), and network attached storage (NAS) devices do not provide authentication services.

Answer 80

B. Deep packet inspection (DPI) is a firewall technique that examines the data carried in packets and not just the protocol headers. While traditional firewalls typically do not support DPI, Next Generation Firewalls (NGFWs) often do. Stateful packet inspection, Network Address Translation (NAT), and virtual private network (VPN) support are all features that are commonly supported by traditional firewall products.

Answer 81

A, B, and C. An AAA server, such as Remote Authentication Dial-In User Service (RADIUS), provides authentication, authorization, and accounting services. Assistance and attenuation are not functions provided by AAA servers.

Answer 82

C. Content filters are a firewall feature that examines the data inside packets, rather than their origin, to locate objectionable material such as pornography. They do not scan IP addresses, nor do they detect typical types of malware. Content filters are not implemented in switches.

Answer 83

D. In most cases, a load balancing router works by processing incoming traffic based on rules set by the administrator. The rules can distribute traffic among a group of servers using various criteria, such as each server’s current load or response time or which server is next in a given rotation. Load balancers typically do not use the hardware configuration of the servers to direct traffic, since this is a factor that does not change.

Answer 84

C. A VoIP gateway is a device that provides a conduit between an IP network and the Public Switched Telephone Network (PSTN). The gateway enables standard telephones connected to the PSTN to place calls using VoIP services on the Internet. A proxy server is an application layer device that provides web browsers and other client programs to access the Internet. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations. A unified threat management (UTM) appliance typically performs VPN, firewall, and antivirus functions.

Answer 85

A and C. Network address translation (NAT) is a network layer device that converts the private IP addresses is all of a client’s transmissions to registered IP address. NAT therefore works for all applications. A proxy server is an application layer device that performs the same type of conversion, but only for specific applications. A Remote Authentication Dial-In User Service (RADIUS) server can provide authentication, authorization, and accounting services for remote access servers. It does not convert IP addresses. A unified threat management (UTM) appliance typically performs VPN, firewall, and antivirus functions. It too does not convert IP addresses.

Answer 86

B. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations. Because the device provides an interface between networks, it is considered to be a type of router, not a switch, a gateway, or a bridge.

Answer 87

B. A virtual PBX is an arrangement in which a telephone company provides the PBX services to a customer but maintains the actual hardware at their own facility. The recent emphasis on cloud computing has led to a number of hosted PBX solutions that use Voice over IP (VoIP) to provide services to customers. Quality of service (QoS) is a technique for prioritizing traffic by tagging packets based on their content. It is not a virtual PBX technique. The Cache Array Routing Protocol (CARP) enables proxy servers to exchange information; it does not provide virtual PBX services. In round-robin DNS, a DNS server contains multiple resource records for the same server name, each with a different IP address representing one of the computers running the server application. When a client resolves the server name, the DNS server accesses each of the resource records in turn so that each address theoretically receives the same number of visitors. This is not a virtual PBX technology.

Answer 88

C. Proxy servers provide network users with access to Internet services, and the unregistered IP addresses on the client computers protect them from unauthorized access by users on the Internet, which satisfies the first objective. The proxy servers also make it possible for network administrators to regulate users’ access to the Internet, which satisfies one of the two secondary objectives. However, the proxy servers cannot assign IP addresses to the client computers, and the plan makes no mention of DHCP or another automatic TCP/IP configuration mechanism. Therefore, the plan does not satisfy the other secondary objective.

Answer 89

A and B. The Control and Provisioning of Wireless Access Points (CAPWAP) protocol and the Lightweight Access Point Protocol (LWAPP) are both protocols that enable wireless controllers to manage and control Thin access points. Lightweight Directory Access Protocol (LDAP) is used by directory services, and Point-to-Point Tunneling Protocol (PPTP) is used for virtual private networking.

Answer 90

B. In many enterprise wireless networks, the access points do not run a full operating system and are called Thin or lightweight APs. The network also has a device called a wireless controller that performs some of the required tasks and manages the APs. A wireless endpoint is another term for a computer or other device that is a client on the wireless network. Hypervisors and demarcation points have nothing to do with wireless networking. A hypervisor creates and manages virtual machines on a host server, and a demarcation point is the interface between a private network and an outside telecommunications service.

Answer 91

A. A multilayer switch is a network connectivity device that function at both layer 2 and layer 3 of the OSI model. At layer 2, the device functions like a normal switch, providing individual collision domains to each connected node and enabling administrators to create multiple VLANs. At layer 3, the device also provides routing capabilities by forwarding packets between the VLANs. Virtual routers, load balancers, and broadband routers are strictly layer 3 devices that can route traffic but cannot create VLANs.

Answer 92

D. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations. It does not distribute traffic among servers. A load balancer is a type of router that forwards traffic with a single IP address to multiple servers in turn. Round-robin DNS is a technique in which a DNS server resolves a name into several IP addresses, each in turn. A Network Load Balancing (NLB) cluster is a group of servers, all running the same application, that distribute incoming traffic among themselves.

Answer 93

B. A load balancer is a type of router that forwards traffic with a single IP address to multiple servers in turn. In most cases, a load balancing router works by processing incoming traffic based on rules set by the administrator. Because a load balancer works with IP addresses, it is a network layer device. Load balancers are not switches, gateways, or firewalls.

Answer 94

A. A Remote Authentication Dial-In User Service (RADIUS) server can provide centralized authentication, authorization, and accounting services for multiple remote access servers, using a single set of user accounts. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations. A load balancer is a type of router that forwards traffic with a single IP address to multiple servers in turn. Intrusion detection systems (IDSs) and intrusion prevention systems (IPSs) can detect and prevent malicious behavior. None of these devices can provide authentication services.

Answer 95

C. Next Generation Firewalls (NGFWs) expand on the packet filtering capabilities of traditional firewalls by adding features such as deep packet inspection (DPI) and intrusion prevention systems (IPSs), as well as inspection of encrypted traffic and antivirus scanning. Remote Authentication Dial-In User Service (RADIUS) servers can provide centralized authentication, authorization, and accounting services. A CSU/DSU is a device that provides a router on a private network with access to a leased line. A proxy server is an application layer service that receives Internet service requests from client computers, reads the application layer protocol data in each request, and then generates its own request for the same service and transmits it to the Internet server the client specifies.

Answer 96

A. A private branch exchange (PBX) switches internal calls and provides access to external lines. A VoIP PBX performs the same tasks as a traditional PBX. A VoIP gateway is the device that provides the conduit between an IP network and the Public Switched Telephone Network (PSTN). A VoIP endpoint is a device that makes use of the VoIP system, such as a computer or handset. A multilayer switch is a data networking device that includes both switching and routing capabilities.

Answer 97

A. Because the client computers use private IP addresses, they are invisible to the Internet, so users outside the private network cannot see or access them. The proxy server has a public IP address so it can participate in service transactions with Internet servers. If the proxy server used a private IP address, it would not be able to access the Internet directly. If the clients used public IP addresses, they would be visible to the Internet and vulnerable to intrusion.

Answer 98

B and C. To provide clients with Internet access, a NAT or proxy server must have direct access to the Internet, which requires using a registered, or public, IP address. Both NAT and proxy servers function as the middleman in transactions between the client computers on a private network and Internet servers. The NAT or proxy server transmits the client’s service request to the Internet server as though it was its own and, after receiving the reply, relays the response back to the client. Because NAT servers function at the network layer, clients can use any application to access the Internet through the server. Proxy servers, however, operate at the application layer and can provide Internet access only to certain types of client applications. Proxy servers are capable of caching web data for later use because they are application layer devices that read the application layer protocol data in the message packets they receive. NAT servers are network layer processes that forward packets with no knowledge of the application layer information in their contents.

Answer 99

A, B, and C. A multilayer switch typically operates at the physical, data link, and network layers, assuming the functions of a switch and a router. The device can conceivably operate at the upper layers, but most do not.

Answer 100

A. Intrusion detection systems (IDSs) are designed to monitor network traffic for anomalies and send notifications to administrators. Uninterruptible power supplies (UPSs), Remote Authentication Dial-In User Service (RADIUS) servers, denial-of-service (DoS) attacks, and Remote Access Service (RAS) servers all have nothing to do with network monitoring.

Answer 101

C. Packet forwarding is a function typically associated with routers and is not a normal function of a UTM appliance. UTM appliances do typically perform VPN, firewall, and antivirus functions.

Answer 102

D. Ethernet uses jumbo frames at the data link layer to transfer large amounts of data more efficiently. Ethernet typically restricts frame size to 1,500 bytes, but jumbo frames enable Ethernet systems to create frames up to 9,000 bytes. Frames are protocol data units associated only with the data link layer, so they do not apply to the network, transport, or application layer.

Answer 103

A and C. iSCSI runs on a standard IP network, and Fibre Channel over Ethernet (FCoE) runs on a standard Ethernet network. Both of these protocols can share a network with LAN traffic, although the use of a quality of service (QoS) mechanism is usually recommended. Fibre Channel and InfiniBand both require a dedicated network medium that does not support LAN traffic.

Answer 104

D. In most virtualization products, when you create multiple virtual machines on one host computer, they can communicate with each other internally using a built-in virtual switching capability. A computer with multiple network adapters can function as a router, but not as a switch. Layer 3 switches can provide virtual routers that connect VLANs together, but not virtual switches. The function that enables VLANs on different switches to communicate is called trunking, not virtual switching.

Answer 105

B. Type I virtualization does not require a host OS, whereas Type II virtualization does. Both Type I and Type II virtualization can use processors with hardware virtualization assistance, but only Type I requires it. The type of virtualization does not impose any limit on the number of virtual machines supported; any limitations are left to the individual implementation. Both Type I and Type II virtualization can share a single processor among virtual machines.

Answer 106

B. You can create virtual local area networks (VLANs) on a virtual switch, just as you can create them on many physical switches. In most cases, virtual components function just like their physical counterparts. Virtual NICs are components of virtual machines and therefore do not provide functions spanning entire networks. Virtual routers function at the network layer and virtual firewalls at the application layer, so neither of these can host VLANs, which operate at the data link layer.

Answer 107

B. Just like physical network interface cards (NICs), virtual NICs have six-byte MAC addresses assigned to them, which enable them to be identified by data link layer protocols. Unlike physical NICs, however, it is typically an easy matter to modify a MAC address on a virtual NIC. Virtual switches, like physical switches, are not addressable devices, so they do not have MAC addresses on an unmanaged network. The hypervisor is the component on a host server that makes virtualization possible, so it does not require a MAC address. Virtual firewalls operate at the application layer, so they do not require data link layer MAC addresses. On a managed network, these devices have a MAC address to communicate with the management console, but addresses are not needed on an unmanaged network.

Answer 108

C. Voice over Internet Protocol (VoIP) is a technology for the transmission of voice communications over IP networks; it is not a SAN protocol. Internet Small Computer Systems Interface (ISCSI), Fibre Channel over Ethernet (FCoE), and Fibre Channel are all SAN protocols.

Answer 109

E. The Internet Storage Name Service (iSNS) is an application that provides iSCSI initiators with automated discovery of targets located on the network. iSNS can also function as a discovery service for Fibre Channel devices. Active Directory, Internet Control Message Protocol (ICMP), and Domain Name System (DNS) are not capable of registering iSCSI targets. iWINS does not exist.

Answer 110

D. The current Fibre Channel standard calls for a maximum data transfer rate of 128 gigabits per second (Gbps), for a nominal throughput of 12,800 megabytes per second (MBps).

Answer 111

A and C. iSCSI runs on a standard IP network, so its traffic can conceivably coexist with LAN traffic. However, the use of a quality of service (QoS) mechanism is strongly recommended, to prevent the two traffic types from interfering with each other. Fibre Channel over Ethernet (FCoE) replaces the bottom two layers of the standard Fibre Channel network with Ethernet physical and data link layer implementations. This makes it possible to run a Fibre Channel SAN using standard Ethernet networking hardware. However, the same issues of traffic coexistence that affect iSCSI apply to FCoE as well. Standard Fibre Channel and InfiniBand SANs cannot coexist with LAN traffic on the same network cable.

Answer 112

B. A NAS device is essentially a file server that connects to a network and provides users with access to shared files. A NAS is a single computer, so it cannot be associated with failover clustering. Just a Bunch of Disks (JBOD) is a simple storage array that provides block-level access to data, whereas NAS devices provide file-level access. Redundant Array of Independent Disks (RAID) is a fault tolerance technology that might be implemented in NAS devices, but it is not the device’s primary function.

Answer 113

A and D. NAS devices are self-contained file servers that connect directly to a standard IP network. A NAS device provides file-level access to its storage devices and includes an operating system and a filesystem. NAS devices are typically not iSCSI targets.

Answer 114

A, B, and D. Because it uses standard Ethernet hardware, Fiber Channel over Ethernet (FCoE) is far less expensive to implement than Fibre Channel, which requires a dedicated fiber-optic network. Because Fibre Channel requires a dedicated network, it cannot coexist with standard IP traffic, whereas FCoE can. Because it is encapsulated in Ethernet frames, FCoE is not routable on IP networks.

Answer 115

A, B, and D. Common Internet File System (CIFS), Network File System (NFS), and Hypertext Transfer Protocol (HTTP) are all file sharing protocols supported by many NAS devices. Remote Direct Memory Access (RDMA) provides high-speed network data transfers, but it is not an application layer file sharing protocol.

Answer 116

C. iSCSI does not include its own flow control mechanism. It runs over a TCP connection, which is the protocol responsible for flow control. Because it runs on any IP network, iSCSI traffic is routable, and it is less expensive to implement. Fibre Channel requires a dedicated network using fiber-optic cable. iSCSI traffic can coexist with standard LAN traffic on a single network, although some type of quality of service (QoS) mechanism is frequently recommended.

Answer 117

A. InfiniBand is a high-end storage infrastructure technology that provides data transfer rates of up to 2.5 Gbps and scalable support for up to 64,000 devices. It is primarily used in high-performance computing environments to replace older bus technologies connecting processors to storage arrays. Fibre Channel, Internet Small Computer System Interface (iSCSI), and Fibre Channel over Ethernet (FCoE) are all SAN technologies, but they are more commonly used in local area network (LAN) environments.

Answer 118

A. The client side of an iSCSI implementation is called an initiator. The storage device to which the initiator connects is called a target. Controller and adapter are not terms used for iSCSI clients or servers.

Answer 119

A. The hypervisor is the hardware or software component responsible for managing virtual machines and providing the virtualized hardware environment on which they run. Virtual servers and virtual switches are components that are part of the virtual network infrastructure enabled by the hypervisor. A virtual private network (VPN) concentrator is a type of router that enables multiple remote clients to connect to a network; it has nothing to do with virtual networking.

Answer 120

A, B, and C. iSCSI runs on a standard IP network; therefore, iSCSI messages are encapsulated using Transmission Control Protocol (TCP) at the transport layer, Internet Protocol (IP) at the network layer, and Ethernet at the data link layer. iSCSI does not use the User Datagram Protocol (UDP).

Answer 121

E. The Fibre Channel standard defines a unique, five-layer protocol stack that does not correspond to the OSI model layers. Therefore, Fibre Channel does not use Ethernet, nor does it use Transmission Control Protocol (TCP), Internet Protocol (IP), User Datagram Protocol (UDP), or any of the other TCP/IP protocols.

Answer 122

B. The Fibre Channel standard defines a five-layer networking stack, with layers numbered FC-0 to FC-4, that does not correspond to the layers of the OSI model. Internet Small Computer System Interface (iSCSI), Point-to-Point Protocol (PPP), and Remote Direct Memory Access (RDMA) all function within the standard OSI model layers.

Answer 123

A. Fibre Channel over Ethernet (FCoE) uses Ethernet frames in place of the bottom two layers (FC0 and FC1) of the Fibre Channel protocol stack. The remaining layers (FC2, FC3, and FC4) use the standard Fibre Channel protocols. FCoE does not use Transmission Control Protocol (TCP), Internet Protocol (IP), User Datagram Protocol (UDP), or any of the other TCP/IP protocols.

Answer 124

C. A computer with a hypervisor, on which you can create virtual machines, is referred to as a host. The virtual machines themselves are called guests. Network attached storage (NAS) refers to a device containing shared drives that is connected to a network. A storage area network (SAN) is a separate network dedicated to shared storage devices.

Answer 125

A. It is true that virtual switches can have unlimited ports, whereas physical switches are limited to the number of physical ports in the device. Both virtual and physical switches can support virtual local area networks (VLANs). Virtual switches can forward traffic to the host server. Physical switches do not always include layer 3 (routing) functionality.

Answer 126

A. Ethernet uses jumbo frames to transfer large amounts of data more efficiently. On a packet-switched network, each packet requires header data, which adds to the network’s transmission overhead. Splitting large files into a great many small packets can lead to so much overhead that network efficiency is impaired. Ethernet typically restricts frame size to 1,500 bytes, but jumbo frames enable Ethernet systems to create frames up to 9,000 bytes. Frames are data link layer protocol data units, so Internet Protocol (IP), operating at the network layer, is not involved in creating them. Fibre Channel and iSCSI are specialized storage area networking protocols that do not use jumbo frames.

Answer 127

E. A virtual firewall is a service or appliance that performs the same functions as a physical network firewall: packet filtering and monitoring. In a virtual environment, firewalls can take the form of software components installed on a guest virtual machine or a hypervisor host system. A firewall can also be incorporated into a virtual switch.

Answer 128

A. Modem-to-modem connections use the existing analog Public Switched Telephone Network (PSTN) network to carry data over standard telephone lines. All modem-to-modem connections are limited to analog signaling and therefore must perform modulation and demodulation. This means that the modems convert digital signals to analog signals before transmitting them over the PSTN network. Modems then convert the digital signals back to analog at the destination. ISDN, DSL, and cable broadband all use digital signaling from end to end.

Answer 129

A. The current industry standard transmission speed for modem communication using PSTN connections is 56 Kbps in one direction and 33.6 Kbps in the other. To achieve 56 Kbps, one of the devices must have a digital connection to the PSTN. ISDN, DSL, and cable broadband all support faster transmission speeds.

Answer 130

B. ISDN has a separate channel, referred to as the D channel, which devices use for control and synchronization. The other channels (or circuits) carry data and are referred to as B channels. Modem-to-modem communication uses in-band signaling, which means that both control/synchronization and data traffic are carried over the same circuit. L2TP and PPTP are tunneling, not WAN, protocols.

Answer 131

C. ISDN BRI is sometimes referred to as 2B+D. B channels are 64-Kbps circuits that carry user data. A single D channel carries control and synchronization information. An ISDN PRI connection has 23 B channels, not 2. DSL does not use B and D channels. T-1 circuits consist of 24 channels, all of which carry data and control information.

Answer 132

D. DSL technology provides higher data rates because it uses frequency ranges that are higher than the standard voice spectrum. DSL connections use from 10 kHz and above, whereas the standard voice spectrum uses 300 Hz to 4 kHz. DSL does not use separate control circuits and does not perform CRC functions. Also, DSL technology is strictly digital and does not require an analog-to-digital conversion.

Answer 133

C. Rate-Adaptive Digital Subscriber Line (RADSL) technology can adjust its rate of transmission based on line conditions. High-bit-rate Digital Subscriber Line (HDSL), Very high-rate Digital Subscriber Line (VDSL), and Internet Digital Subscriber Line (IDSL) do not use rate adaptive transmission.

Answer 134

D. CATV networks use broadband signaling, which enables many signals to occupy the same channel. DSL and ISDN do not use broadband signaling. SONET is a physical layer standard that defines fiber-optic connections.

Answer 135

D. In this scenario, there are 10 users with BRI connections, each of which has its two B channels combined to provide a 128 Kbps transfer rate per user. To support simultaneous connections to the corporate site, Alice will need to install and configure a single PRI link to support the aggregation of multiple B channel connections. A single PRI link has 23 B channels and 1 D channel. Therefore, the router can support up to 11 inbound BRI sessions simultaneously, which is more than enough. Installing a single BRI at the corporate site would not enable multiple simultaneous BRI connections, and installing five BRI links, for a total of ten 64 Kbps B channels, would not support the ten 128 Kbps sessions that are required. Installing multiple PRI links is unnecessary since the site only has to support ten inbound BRI connections.

Answer 136

B. For this scenario, the best solution is a dedicated leased line connection. This is because the bandwidth requirements are constant and the data transfer rates are high. To support the 40 Mbps data rate, Ed should recommend a T-3 dedicated leased line, running at 44.735 Mbps. Standard modem connections, ADSL, and an ISDN PRI connection are all too slow.

Answer 137

D. In this scenario, the best solution is for Ralph to use his existing CATV service the remote connection. CATV offers faster data rates than standard modem-to-modem service and supports VPN connections. A dedicated fractional T-1 line is expensive and is not typically used for remote user connections. Since Ralph’s telephone lines are not run through conduit and the distance to the central office is more than 18,000 feet, he probably cannot use DSL technology, because it requires good-quality lines and close proximity to a central office.

Answer 138

E. For this scenario, the only solution that meets all the company’s needs is an ISDN PRI connection. All of the specified options, except for the PSTN modem connection, provide sufficient bandwidth for the application. However, only the ISDN and PSTN links can be disconnected when not in use. Therefore, ISDN is the only possibility.

Answer 139

A. PSTN is an analog, circuit-switched network. ISDN, CATV, DSL, and SONET are all digital networks.

Answer 140

A and B. Circuit-switching WAN technologies set up and maintain connections between end systems for the duration of a session. The WAN technologies that can use this type of connection are PSTN and ISDN. Leased lines, such as a T-1, are dedicated connections. DSL uses packet switching, not circuit switching.

Answer 141

D. In a DSL connection, a signal splitter is needed at the customer site to separate the lower frequency voice range from the higher frequencies used by data traffic. The higher frequency signals are handled at the central office by a DSLAM device. Lower frequency signals carrying voice traffic are handled at the central office by a CODEC device. A signal terminator is not required by DSL.

Answer 142

B and C. There are two factors that affect DSL transmission rates. The first is the distance to the nearest central office, and the second is the condition and quality of the line. For DSL to achieve higher data rates, the site must be close to the central office and use good-quality lines for signal transmission. The other options are not factors relating to DSL transmission.

Answer 143

A and D. PPP supports both clear text and encrypted password authentication. It also supports multiple network layer protocols.

Answer 144

B. A demarcation point, or demarc, is the place where an outside telecommunications service meets a customer’s private network, which is typically where the service enters the building. The demarc is also the place where the responsibility of the network administrator ends. If a problem occurs outside the demarc, it is up to the service provider to fix it. Inside the demarc, it is the network administrator’s problem.

Answer 145

D. Point-to-Point Protocol over Ethernet (PPPoE) is designed to connect multiple computers to a remote network using an Ethernet LAN and broadband technology, while establishing a separate PPP connection between each computer and a given remote service. The Extensible Authentication Protocol (EAP) is a shell protocol that enables systems to use various types of authentication mechanisms. The primary advantage of EAP is that it enables a computer to use mechanisms other than passwords for authentication, including public key certificates, smartcards, and biometric devices, such as fingerprint scanners. The Remote Desktop Protocol (RDP) was designed to enable Remote Desktop Services servers and clients to communicate. It is an application layer protocol that has nothing to do with extending PPP connections to Ethernet networks. IPsec provides security for IP network communications; it does not extend PPP connections to Ethernet networks.

Answer 146

B. The word symmetric in Symmetric Digital Subscriber Line means that the service provides equal amounts of bandwidth in both directions. The asymmetric in Asymmetric Digital Subscriber Line means that the service provides more downstream bandwidth than upstream. Cable and satellite services are also asymmetric, providing more bandwidth downstream than upstream.

Answer 147

A. PSTN is the standard telephone network, an analog, circuit-switched service. ISDN, DSL, CATV, SONET, and ATM are all digital networks.

Answer 148

D. The network interface device (NID) at the demarcation point of a leased line can be a simple RJ45 jack, but many service providers install smart jacks, which can also provide signal conversion, diagnostic testing, and other capabilities. Punchdown blocks, 110 blocks, and channel service unit/data service units (CSU/DSUs) are all telecommunications components located inside the demarc, on the subscriber’s private network.

Answer 149

B and C. ISDN and DSL are both remote access technologies that enable users to transmit voice and data simultaneously. To do this, DSL splits the lower analog frequency (voice) range from the higher digital frequency (data) range, whereas ISDN provides multiple data channels (called B channels) that allow for both voice and data transmissions. Broadband cable television networks can often support simultaneous voice and data communications, but they use Voice over IP (VoIP) to carry voice traffic over the Internet, not the PSTN. Dial-up connections and SONET do not support the simultaneous transmission of voice and data.

Answer 150

D. The demarc, or demarcation point, is the place where a service enters the building and where the service provider’s physical layer responsibility ends. The patch panel, the switch, and the firewall are all inside the network, and they are the responsibility of the subscriber.

Answer 151

D. Extensible Authentication Protocol (EAP) is a shell protocol used with Point-to-Point Protocol (PPP), which enables systems to support various types of authentication mechanisms. The primary advantage of EAP is that it enables a computer to use mechanisms other than passwords for authentication, including public key certificates, smartcards, and biometric devices, such as fingerprint scanners. Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) support only password authentication. Point-to-Point Tunneling Protocol (PPTP) is a virtual private networking (VPN) protocol, not an authentication protocol.

Answer 152

E. A T-3 leased line connection is the equivalent of 28 T-1 connections. Each T-1 consists of 24 channels, so a T-3 has a total of 672 channels (28 × 24).

Answer 153

A and B. PPP provides a physical and data link layer connection between two end systems. The network control protocols (NCPs) associated with PPP facilitate the use of network layer protocols, such as IP, but they do not operate at the network layer themselves. PPP does not operate at the upper layers of the OSI model.

Answer 154

C. A T-3 leased line connection is the equivalent of 28 T-1 connections. Each T-1 consists of 24 channels, so a T-3 has a total of 672 channels (28 × 24), for an overall transfer rate of 44.736 Mbps.

Answer 155

D. Asynchronous Transfer Mode (ATM) is a cell-switched protocol that is designed to carry voice, data, and video traffic by splitting it into uniform 53-byte cells. To this degree, it can be considered a packet-switched service. However, it is unlike traditional packet-switched protocols, which use variable-sized packets. ATM can also be called a circuit-switched service, because the end systems must create a virtual circuit before they transfer any data. Public Switched Telephone Network (PSTN) and T-1 leased lines are both circuit-switched network types, while Metropolitan Ethernet is packet-switched.

Answer 156

B. The Synchronous Optical Networking (SONET) standard defines a base data transfer rate of 51.84 Mbps, which is multiplied at the various optical carrier levels. An OC-3 connection therefore runs 155.52 Mbps, an OC-12 at 622.08 Mbps and so forth. The Synchronous Digital Hierarchy (SDH) is the European equivalent of SONET. Integrated Services Digital Network (ISDN) is a service that combines voice and data services using the Public Switched Telephone Network (PSTN), and Asynchronous Transfer Mode (ATM) is cell-switched protocol defining a combined voice, data, and video service.

Answer 157

B. Frame relay is a packet switching service that uses a single leased line to replace multiple leased lines by multiplexing traffic through a cloud. The service can create virtual circuits connecting the subscriber’s network to multiple destinations, eliminating the need for a dedicated leased line to each remote site. An E-1 is the European equivalent to a T-1 leased line, which does not replace multiple T-1s. Asynchronous Transfer Mode (ATM) is a cell-switching WAN technology, and Point-to-Point Protocol (PPP) is a protocol that provides a data link layer connection between two end systems. Neither is a replacement for multiple T-1s.

Answer 158

B. Multiprotocol Label Switching (MPLS) is a data transfer mechanism that assigns labels to individual packets and then routes the packets based on those labels. Frame relay, Asynchronous Transfer Mode (ATM), and Point-to-Point Protocol over Ethernet (PPPoE) do not assign labels to packets.

Answer 159

C. The term broadband has nothing to do with the width of the cable. However, the term as been used to refer to a transmission medium that carries multiple signals, that carries a wide range of frequencies, that is faster than a dial-up modem, and that provides an always-on, high-speed connection to the Internet.

Answer 160

C and D. The two types of ISDN services are Basic Rate Interface (BRI) and Primary Rate Interface (PRI). Terminal Equipment 1 (TE1), terminal adapter (TA), Network Termination 1 (NT1) are all terms for ISDN hardware devices.

Answer 161

A and C. A Session Initiation Protocol (SIP) trunk provides a connection between the private and public domains of a unified communications network. A VoIP gateway provides a connection between an IP network and the Public Switched Telephone Network (PSTN). Both of these provide a conduit between a subscriber’s private network and the network furnished by a service provider. A CSU/DSU is a device that provides a router on a private network with access to a leased line. A smart jack provides signal conversion, diagnostic testing, and other capabilities to leased line subscribers. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations.

Answer 162

B. VPN typically enables remote clients to connect to a VPN router at a central site, much like the star topology of a local area network, in which computers are all connected to a central switch. Dynamic multipoint virtual private network (DMVPN) is a technology that creates a mesh topology between the remote VPN sites, enabling the remote sites to connect directly to each other, rather than to the central VPN server. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations. A Session Initiation Protocol (SIP) trunk provides a connection between the private and public domains of a unified communications network. Multiprotocol Label Switching (MPLS) is a data transfer mechanism that assigns labels to individual packets and then routes the packets based on those labels.

Answer 163

B. Attenuation is the weakening of a signal as it travels over a transmission medium. Fiber-optic cables can carry signals for great distances with little attenuation, far less than any copper medium. Wireless and satellite media, by transmitting signals through air, suffer the most attenuation of any of these options.

Answer 164

A and D. PPPoE encapsulates PPP within Ethernet frames, not the other way around. The two stages of the PPPoE connection process are discovery and session. PPPoE does enable multiple users to share an Internet connection, and it requires a PPPoE server that initiates the PPP connection to the ISP’s network.

Answer 165

A. Synchronous Digital Hierarchy (SDH) is the European equivalent of SONET. Optical carrier 3 (OC-3) is one of the SONET data rates. E-3 is the European equivalent of the T-3 connection in the United States. Asynchronous Transfer Mode (ATM) is a cell-switched protocol that is designed to carry voice, data, and video traffic by splitting it into uniform 53-byte cells.

Answer 166

B. A channel service unit/data service unit (CSU/DSU) is a device that provides a LAN router on a private network with access to a leased line WAN connection. Quad Small Form-Factor Pluggable (QSFP) is a standard for a type of modular transceiver, often used on fiber-optic installations. A Session Initiation Protocol (SIP) trunk provides a connection between the private and public domains of a unified communications network, such as a LAN and the Public Switched Telephone Network (PSTN). An intrusion detection system/intrusion prevention system (IDS/IPS) is a network hardware or software security appliance that detects malicious activity and attempts to block it.

Answer 167

D. A subscription to part of the T-1 leased line is called a fractional T-1 service. This service enables you to purchase some of the 24 DS0 channels in a T-1 connection. An E-1 is the European version of a T-1. A B channel is part of an Integrated Services Digital Network (ISDN) service, not a T-1. An OC-1 is a fiber-optic connection on the Synchronous Optical Network (SONET) service.

Answer 168

B. MPLS is a data-carrying service that is often said to operate between the data link layer and the network layer. It is therefore sometimes called a layer 2.5 protocol. MPLS can be used to carry IP datagrams as well as Ethernet, Asynchronous Transfer Mode (ATM), and Synchronous Optical Network (SONET) traffic.

Answer 169

D. An OC-1 connection provides the fastest transfer rate at 51.84 Mbps. An E-1 connection is 2.048 Mbps. A T-3 is 44.736 Mbps, and a T-1 is 1.544 Mbps.

Answer 170

C. The Data Over Cable Service Interface Specification (DOCSIS) is a telecommunications standard that defines the manner in which data is to be transmitted over a cable television system. DOCSIS does not apply to dial-up modem, Digital Subscriber Line (DSL), and Integrated Services Digital Network (ISDN) connections.

Answer 171

B and C. Frame relay services offer permanent virtual circuits (PVCs) and switched virtual circuits (SVCs). SRV is a resource record type in the Domain Name System (DNS), and an ultra-polished connector (UPC) is a type of fiber-optic cable connector.

Answer 172

C. Cable broadband and DSL subscribers typically connect to ISP networks that run Ethernet, but Ethernet has no built-in authentication or encryption mechanisms. PPP has the ability to use external authentication and encryption protocols, so by encapsulating PPP within Ethernet frames, users are able to log on to the ISP network securely. PPPoE has nothing to do with the subscriber’s internal home network, which can run standard Ethernet. PPPoE does not replace the Ethernet frame with PPP, so it would not reduce network overhead. LAN users do not share files using PPP.

Answer 173

C and D. Cable broadband and DSL subscribers typically connect to ISP networks that run Ethernet, but Ethernet has no built-in authentication or encryption mechanisms. PPP has the ability to use external authentication and encryption protocols, so by encapsulating PPP within Ethernet frames, users are able to log on to the ISP network securely. Leased lines, such as T-1s, and Synchronous Optical Network (SONET) connections do not use Ethernet connections, so they have no need for PPPoE.

Answer 174

C. A smart jack is a device located at the demarcation point of a leased line that can provide additional functions, such as signal conversion, diagnostic testing, and other capabilities. A Session Initiation Protocol (SIP) trunk is a connection to a Voice over Internet Protocol (VoIP) service provider. A media converter is a local area networking devices that connects different cable types to the same network. An AAA server provides authentication, authorization, and accounting services for remote access servers.

Answer 175

D. Frame relay is a packet switching service that uses a single leased line to replace multiple leased lines by multiplexing traffic through a cloud. Asynchronous Transfer Mode (ATM) uses a switched fabric, but it is not referred to as a cloud. A fractional T-1 is part of a leased line that connects two points, so there is no switching involved and no cloud. SONET is a physical layer standard that defines fiber-optic connections; it does not call for switching or use the term cloud.

Answer 176

A. Asynchronous Transfer Mode (ATM) transfers data using uniformly sized cells rather than same-sized packets. Frame relay uses variable-sized packets, and Point-to-Point Protocol over Ethernet (PPPoE) uses variable-sized Ethernet frames. A T-1 is a circuit-switched connection that does not use packets or cells.