CHAPTER 3 DO I KNOW THIS ALREADY

Question 1

Which of the following best describes the main function of OSI Layer 1 as used in WANs?

a. Framming
b. Delivery of bits from one device to another
c. Addressing
d. Error detection

Answer 1

b

Question 2

In the cabling for a leased line, which of the following typically connects to a four-wire line provided by a telco?

a. Router serial interface without CSU/DSU
b. CSU/DSU
c. Router serial interface with internal transceiver
d. Switch serial interface

Answer 2

b

Question 3

Which of the following is an accurate speed at which a leased line can operate in the United States?

a. 100 Mbps
b. 100 Kbps
c. 256 Kbps
d. 6.4 Mbps

Answer 3

c

Question 4

Which of the following fields in the HDLC header used by Cisco routers does Cisco add, beyond the ISO standard HDLC?

a. Flag
b. Type
c. Address
d. FCS

Answer 4

b

Question 5

2 routers, R1 and R2, connect using an Ethernet over MPLS service. The service provides point-to-point service between these 2 routers only, as a Layer 2 Ethernet service. Which of the following are the most likely to be true about this WAN? (Choose 2 answers)

a. R1 will connect to a physical Ethernet link, with the other end of the cable connected to R2.
b. R1 will connect to a physical Ethernet link, with the other end of the cable connected to a device at the WAN service provider point of presence.
c. R1 will forward data link frames to R2 using HDLC header/trailer.
d. R1 will forward data link frames to R2 using Ethernet header/trailer.

Answer 5

b, d

Question 6

Which of the following Internet access technologies, used to connect a site to an ISP, offers asymmetric speeds? (Choose 2 answers)

a. Leased lines.
b. DSL
c. Cable Internet
d. BGP

Answer 6

b, c

Question 7

Fred has just added DSL service at his home, with a separate DSL modem and consumer-grade router with a4 Ethernet ports. Fred wants to use the same old phone he was using before the installation of DSL. Which is most likely true about the phone cabling and phone used in his new DSL installation?

a. He uses the old phone, cabled to one of the router/switch device’s Ethernet ports.
b. He uses the old phone, cabled to the DSL modem’s ports.
c. He uses the old phone, cabled to an existing telephone port, and not to any new device.
d. The old phone must be replaced with a digital phone.

Answer 7

c