Fundamentals of WANs

Question 1

The term _____ _____ refers to the fact that the company using the _____ ______ does not own the line, but instead pays a monthly lease fee to use it.

Answer 1

leased line

Question 2

Many people today use the generic term ______ _____

to refer to a company that provides any form of WAN connectivity, including Internet services.

Answer 2

Service provider

Question 3

The physical link requires a function called a ____/____.

Answer 3

Channel service unit/data service unit

CSU/DSU

Question 4

The ____/_____ can either be integrated into the serial interface card in the router or sit outside the router as an external device.

Answer 4

CSU/DSU

Question 5

Each site has ______ ________ _______, which includes the router, serial interface card, and CSU/DSU.

Answer 5

Customer Premises Equipment (CPE)

Question 6

Each router uses a ______ ______ card that acts somewhat like an Ethernet NIC, sending and receiving data over the physicla link.

Answer 6

serial interface

Question 7

The serial cables normally used between a router and an external CSU/DSU are called ____ ______ ____ cables.

Answer 7

Data Terminal Equipment (DTE) Cables

Question 8

To create a physical WAN link in a lab, you need two serial cables: one serial DTE cable, plus a similar but slightly different matching ____ _______ _____ cable.

Answer 8

Data Communications Equipment (DCE) Cable

Question 9

The ______ ______ ______ cable also does the equivalent task of an Ethernet crossover cable by swapping the transmit and recieve wire pairs.

Answer 9

Data Communications Equipment (DCE)

Question 10

The CSU/DSU normally provides a function called _______ , in which it tells the router exactly when to send each bit through signaling over the serial cable.

Answer 10

clocking

Question 11

A router serial interface can provide clocking, but the router does not do so unless configured with the _____ ______ command.

Answer 11

Clock Rate

Question 12

The two most popular data link layer protocols used for leased lines between two routers are __________ and __________.

Answer 12

High-Level Data Link Control (HDLC) and Point-to-Point Protocol (PPP)

Question 13

All ____ ______ protocols perform a similar role: to control the correct delivery of data over a physical link of a particular type.

Answer 13

data link

Question 14

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

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

Answer 14

b. Delivery of bits from one device to another

Question 15

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

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

Answer 15

b. CSU/DSU

Question 16

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 Kbps

Answer 16

c. 256 Kbps

Question 17

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 17

b. Type

Question 18

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

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 an HDLC header/trailer.
d. R1 will forward data link frames to R2 using an Ethernet header/trailer

Answer 18

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
d. R1 will forward data link frames to R2 using an Ethernet header/trailer

Question 19

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

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

Answer 19

b. DSL

c. Cable Internet

Question 20

Fred has just added DSL service at his home, with a separate DSL modem and consumer-grade router with four 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 with 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 20

c. He uses the old phone, cabled to an existing telephone port, and not to any new device.