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ITT Tech Tucson NT 1210 Chapter 7 1)A user of a home telephone picks up her phone and makes a telephone call to a friend’s home telephone in another part of town

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ITT Tech Tucson

NT 1210

Chapter 7

1)A user of a home telephone picks up her phone and makes a telephone call to a friend’s home telephone in another part of town. Which of the following is likely to be true about this call? a. It uses a single pair of wires on the local loop at each end of the call. b. It uses a telco service called packet switching. c. It uses digital circuits at least on the part of the call from the CO to the phone that made the phone call. d. None of the answers is correct.

 

2.            Which of the following are services that telcos have offered as WAN services over the years? (Choose two answers.) a. Switched analog circuits b. Dedicated digital circuits c. Partition switching d. Telekinetic-division multiplexing

 

 

3.            This chapter claims that IP routers work well as devices that connect to many different types of interfaces, including LANs and WANs. Which of the following answers list the reasons why routers do well in this role? (Choose two answers.)   a. Routers have much faster CPUs and can do the hard work to translate the incoming data-link header into the outgoing data-link header format. b. Router vendors sell many different types of physical interface cards, so the routers have the right physical connectors to connect to different types of networks.   c. Routers use Layer 3 and ignore Layers 1 and 2. d. Routers discard old data-link headers and insert new data- link headers as part of their logic, which treats each interface’s lower-layer details as independent from each other.

 

 

4.            An enterprise network has many routers that connect to both a LAN as well as the WAN. Which one of the following statements best describes how routers typically use and think about their WAN connections? a. As a destination where end-user hosts reside b. As a transport service to deliver IP packets to the next IP router c. As nothing, because routers ignore Layers 1 and 2 d. As an interesting and complex technology-filled network of its own, with such features as circuit switching, packet switching, SONET, ATM, and others

 

 

5.            An enterprise builds a WAN design on paper. The main site, where all the servers sit, is shown in the center of a network diagram. The WAN has a leased line from that site to every remote site, with the remote sites drawn around the edges of the drawing in a big circle. None of the

 remote sites have a leased line directly between them. Which of the following terms is most typically used to describe this WAN topology? a. Multipoint b. Star c. Point-to-point d. Hub-and-spoke

 

 

6.            A U.S.-based company wants to order a leased line between two sites, with the leased line using the traditional T-carrier DS0, DS1, and DS3 types of lines. Which of the following answers describe the available speeds and distances for the leased line? (Choose two answers.) a. No longer than 62 miles (100 kilometers) for up to T1 speed b. No faster than 43.736 Mbps (T3)

c. 64 Kbps, 1.544 Mbps, and any speed in between d. No literal distance limitation

 

 

7.            A telco customer has purchased a T1 leased line between two sites. The customer has already bought a router for one site, with a serial interface card with a built-in CSU/DSU. Which of the following answers lists other physical parts that the customer will need for that site’s installation of the T1 leased line? a. A patch cable with RJ-48 connectors b. A serial cable c. An external CSU/DSU d. A demarc

 

 

8.            A telco customer has a T1 leased line between two sites, called sites A and B. The telco has several switches between sites A and B that use T3 trunks. These switches use the T3 trunks along with time-division multiplexing (TDM) to create the leased line from site A to B. Which of the following answers is true about how TDM works in this design?  a. The switches map the T1 customer lines to a T1 channel inside the T3 trunks. b. The switches interpret the customer bits as packets and forward the packets to the correct destination over the T3 trunks. c. The switches map the T1 customer lines to one of 28 different frequencies in the T3 trunks. d. The switches perform a digital-to-analog (D/A) conversion and send the bits over a unique analog frequency over the T3 trunks.

 

 

9.            A telco network has TDM switches in the CO, ready to support T1 leased lines to customer sites. Two such switches have a single T3 trunk connecting the two switches, set aside to support T1s that run just between those two CO switches. Which of the following answers best describes

 the number of customer T1s the telco can support with these switches and the trunk? a. 20 b.

24 c. 28 d. No exact number; it depends on how much time the customer T1s sit idle.

 

 

10.          A customer ordered a full T1 leased line between two sites. The telco implemented that leased line in its network using the T-carrier technology discussed in this chapter, with DS1 and DS3 lines plus switches that use time-division multiplexing (TDM) logic. Into which of the following general WAN categories does this service fit? a. Ethernet switching b. Packet switching c. Label switching d. Circuit switching

 

 

11.          A telco customer orders a leased line between sites A and B, with a requested speed of 1.024 Mbps. The customer plans to use an external CSU/DSU at each site. The telco uses only T-carrier technology and none of the more modern options like SONET, ATM, MPLS, or Metro Ethernet. Which of the following answers is true about the speeds used on this link? a. The physical line between the telco CO and site A uses a line speed of 1.024 Mbps + 8 Kbps for overhead. b. The physical line between the telco CO and site B uses a line speed of 1.544 Mbps. c. The telco rejects the request for the leased line because it is an unsupported speed.   d. The CSU/DSU at site A uses a bit rate of 1.024 Mbps when sending data over the line toward the telco CO.

 

 

12.          A telco customer orders a leased line between sites A and B, with a requested speed of 512 Kbps. The customer plans to use an external CSU/DSU at each site. The telco uses only T-carrier technology and none of the more modern options like SONET, ATM, MPLS, or Metro Ethernet.

Which of the

following answers is true about the speeds used between the router and the CSU/DSU? a. The CSU/DSU controls the router’s sending and receiving speeds using clocking. b. The bit rate over the serial cable is 1.536 Mbps (T1 speed minus 8 Kbps overhead). c. There is no bit rate, because the telco rejects the order because of the speed not matching any of the T-carrier line speeds. d. The CSU/DSU and router are peers with regard to clocking, each sending at the speeds configured on each device, with the receiving device being slaved to the sending device’s clocking.

 

 

 

13.          Which of the following answers are true about DS1 framing and channels? (Choose two answers.) a. Each frame has 193 bits. b. The frame holds 24 bits, one per channel, plus overhead. c. The frame groups 8 bits together for each of 24 channels, plus overhead. d. If the customer ordered a leased line that ran at 768 Kbps (about half the T1 line rate) the number of frames per second would be about 4000.

 

 

14.          Which of the following data-link protocols was created to be used on leased lines, with support for multiple Layer 3 protocols by including a Type field that identifies the type of packet inside the data-link frame? a. HDLC b. LAPF c. PPP d. SDLC

 

 

15.          Which fields that exist in both the HDLC and PPP headers have such relatively small use in point-to-point leased lines today, to the point that the PPP standard actually allows the nodes to simply not bother to include these fields when sending PPP frames? (Choose two answers.) a. Flag  b. Address c. Control d. FCS

 

 

16.          Think about the differences in circuit switching using the T-carrier system (ignoring analog circuit switching) versus packet switching. Which of the following answers are true about packet switching, but not about circuit switching? (Choose two answers.)   a. The telco physical links are digital circuits. b. The telco switch can queue the data waiting on the congested outgoing trunk to become available. c. The trunks between switches fit the bits into logical time channels on the trunk. d. The switches look at the bits to find an address, and use that address to make a choice of where to send the bits.

 

 

17.          In a Frame Relay network, which of the following terms refers to the customer router that connects to the Frame Relay network? a. DCE b. POP c. DTE d. Access link

 

 

18.          Which of the following answers is not true about a Frame Relay PVC? a. Identified by the LAPF header DLCI field b. Defined by the telco ahead of time, when the customer orders the service c. Must exist between two routers before the routers can send Frame Relay frames directly to each other d. Triggers the telco to create a telco leased circuit to support each corresponding PVC

 

 

19.          A new Frame Relay customer is considering two competing Frame Relay designs for his WAN. One design uses a full-mesh topology of PVCs between the 20 routers. The second design uses a partial mesh that looks like a hub-and-spoke design. Assuming that all other technical details not mentioned in this question are the same when comparing the two designs, which of these answers are true about the partial-mesh design, but not true about the full-mesh design? (Choose two answers.) a. Not all routers can send a Frame Relay frame directly to each other.

b. Frame Relay frames will be forwarded by the network based on the DLCI field in the Frame Relay header. c. The price should be lower. d. Users at spoke sites will not be able to send emails to each other.

 

 

20.          Which two of the following WAN services make good use of protocols that enterprises have used for many years, with those protocols being expanded and enhanced to create new types of WAN services? (Choose two answers.)   a. ATM   b. MPLS   c. Metro Ethernet   d. PPP