Chapter 3 Practice Test:

3 ( PC1 will use an Ethernet header, ther first router will use an HDLC header, and the second router will use an Ethernet header, for a total of three.)

How many different layer 2 headers will be used to encapsulate one packet sent by PC1 to PC2? 4 3 2 None. HDLC doesn't use Ethernet Headers. 1

CSU/DSU

In the cabling for a leased line, which of the following typically connects to a four-wire line provided by a telco? CSU/DSU Router serial interface with internal transceiver Router serial interface without internal CSU/DSU Switch serial interface

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

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

The Type field in the header

How does the receiver of an HDLC frame know what has been encapsulated within that frame? Based on the FCS field The Type field in the header Based on the Flag field HDLC only encapsulates IPv4 From the IP address (IPv4, IPv6, and so on)

a , c (The physicall installation uses a model in which each router uses a physical Ethernet link to connect to some SP device in an SP facility called a point of presence (PoP). The Ethernet link does not span from each customer device to the other. From a data-link perspective, both routers use the same Ethernet standard header and trailer used on LANS; HDLC does not matter on these Ethernet WAN links.)

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 answers.) a.) R1 will forward data-link frames to R2 using an Ethernet header/trailer. b.) R1 will connect to a physical Ethernet link, with the other end of the cable connected to R2 c.) 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 HDLC header/trailer.

5

Based on the diagram, host A sends a packet to server B. The two serial links use HDLC, while the rest are Ethernet. How many times does a router re-encapsulate the original IP packet into a new data link frame? 5 6 4 3

Telephone cable

Refer to the diagram. What type of physical cable is used for the connection referenced in the diagram? Triaxial cable Telephone cable Fiber-optic cable Coaxial cable

c.) Used for error detection

What is the purpose of the FCS field in an HDLC frame? a.) Used to indicate to the receiving device that a new frame is arriving b.) Used for identifying the type of L3 payload being carried in the frame c.) Used for error detection d.) Identifies the destination L2 address for the frame e.) Specifies the destination IP address for the frame

a.) DSL b.) Cable Internet

Which of the following Internet access technologies, used to connect a site to an ISP, offers asymmetric speeds? (Choose two answers.) a.) DSL b.) Cable Internet c.) Leased lines d.) BGP

a, d, c

Which of the following are examples of common Internet access links? (select 3) a.) DSL b.) HDLC c.) PPP d.) Cable e.) Leased line

Type

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

256 Kbps

Which of the following is an accurate speed at which a leased line can operate in the United States? 256 Kbps 6.4 Mbps 100 Kbps 100 Mbps