Cisco 100-101 Set 3

Front 1

1. 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

Back 1

b. Delivery of bits from one device to another

Front 2

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 internal CSU/DSU
b. CSU/DSU
c. Router serial interface with internal transceiver
d. Switch serial interface

Back 2

b. CSU/DSU

Front 3

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

Back 3

c. 256 Kbps

Front 4

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

Back 4

b. Type

Front 5

5. 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 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.

Back 5

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.

Front 6

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

Back 6

b. DSL
c. Cable Internet

Front 7

7. 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.

Back 7

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

Front 8

A customer has a WAN link installed between two sites. Explain the size of the cables with the new equipment vs the WAN link

Back 8

Short lines from CPE to CSU/DSU, then long WAN links between sites

Front 9

What does CSU stand for?

Back 9

Channel service Unit

Front 10

What does DSU stand for?

Back 10

Data service unit

Front 11

What does the cable from the telephone company look like, and what type of connector does it use?

Back 11

Cable from telco uses a 4-wire cable with RJ-48 connector

Front 12

What type of cable goes from router to CSU/DSU?

Back 12

DTE cable

Front 13

What does DTE stand for?

Back 13

Data terminal Equipment

Front 14

What kind of cable goes from the DTE cable to another router?

Back 14

DCE cable

Front 15

What does DCE stand for?

Back 15

Data Communications Equipment

Front 16

What provides clocking for the WAN link?

Back 16

CSU/DSU

Front 17

From a networking model standpoint, what does a leased line provide?

Back 17

Leased line only provides layer 1 transport - Companies supply their own protocols

Front 18

What protocols are used over a WAN link?

Back 18

Typically HDLC or PPP

Front 19

What does HDLC stand for?

Back 19

High-Level Data Link Control

Front 20

What does PPP stand for?

Back 20

Point-to-Point Protocol

Front 21

What is HDLC?

Back 21

A bit-oriented synchronous data link layer protocol developed by the International Organization for Standardization
It has similar fields to Ethernet, such an address field. The Destination is implied

Front 22

Why does HDLC only have a sending address field?

Back 22

The destination address is implied. The source address is from when Telcos offered multidrop circuits

Front 23

Name the fields for a HDLC packet

Back 23

Flag
Address
Type
FCS

Front 24

What is the purpose of the Flag field in a HDLC packet, and how is it similar to Ethernet?

Back 24

It is similar to the Ethernet Preamble field, as it provides a recognizable bit pattern the receiving nodes recognize as a new frame is arriving

Front 25

What is the purpose of the Address field in a HDLC packet, and how is it similar to Ethernet?

Back 25

It is similar to the Destination Address field in Ethernet, as it Identifies the destination device

Front 26

What is the purpose of the Type field in a HDLC packet, and how is it similar to Ethernet?

Back 26

The Type field, like Ethernet, Identifies the type of Layer 3 packet encapsulated inside the frame – It is a Cisco Proprietary field

Front 27

What is the purpose of the FCS field in a HDLC packet, and how is it similar to Ethernet?

Back 27

The FCS field, like Ethernet is used by the error detection process – it is the only trailer field

Front 28

What is the size of the HDLC Flag field?

Back 28

1 Byte

Front 29

What is the size of the HDLC Address field?

Back 29

1 Byte

Front 30

What is the size of the HDLC Control field?

Back 30

1 byte

Front 31

What is the size of the HDLC FCS field?

Back 31

2 bytes

Front 32

Regarding symmetry, compare and contrast leased lines vs. consumer grade lines

Back 32

Leased Lines tend to be symmetric, while DSL and Cable tend to be asymmetric
Businesses tend to use Leased lines

Front 33

How is DSL physically structured?

Back 33

Line goes from cable modem at subscriber to Central Office (CO)
Line goes to a DSLAM and splits to PSTN and Internet

Front 34

How is Cable Internet physically structured?

Back 34

Like DSL, line goes from a customer's cable modem to the CO

Front 35

What does Leased Circuit/circuit refer to?

Back 35

It is the generic name for the electrical circuit between two endpoints

Front 36

What does Serial line/serial link refer to?

Back 36

Refers to the serial interfaces, where the bits flow serially

Front 37

How is a Point to point link/line physically structured?

Back 37

Topology stretches between (only) two points

Front 38

What is the speed of a T1Leased line?

Back 38

It transmits at 1.544 Mbps

Front 39

What does Wan link/link refer to?

Back 39

General terms for WAN – no specific technology indicated

Front 40

What does Private Line mean?

Back 40

Data cannot be copied by other customers

Front 41

Explain EoMPLS

Back 41

Ethernet over Multiprotocol label switching - Provides an Ethernet WAN link between two sites. It is a Point-to-point connection between two WAN devices that behaves like a fiber Ethernet link. AKA Ethernet emulation. Uses Ethernet header and trailer for transport

Front 42

Explain what a Leased Line is and how it works.

Back 42

A serial communications circuit between two points, provided by some service provider, typically a telephone company (telco). Because the telco does not sell a physical cable between the two endpoints, instead charging a monthly fee for the ability to send bits between the two sites, the service is considered to be a leased service.

Front 43

Define Serial Interface

Back 43

A type of interface on a router, used to connect to some types of WAN links -- particularly leased lines and Frame Relay access Links

Front 44

Define Wide-area Network

Back 44

A part of a larger network that implements mostly OSI Layer 1 and 2 technology, connects sites that typically sit far apart, and uses a business model in which a consumer (individual or business) must lease the WAN from a service provider (often a telco).