CCNA Common WAN Questions & Answers with Explanation

By | December 1, 2017

This is an Updated CCNA exam question (2017). You might see a different IP addressing, configuration and Port allocation.
As usual, take time to read through the question THRICE if you can clearly understand what Cisco wants you to do.

Note: This Common WAN Questions & Answers are used for demonstration purposes only, you might see different IP addressing, configuration and Port allocation in the real CCNA exam. But it all works the same way, try and understand the question.

Question 1.

Which of the following devices’ primary function to configure the clock rate on a point-to-point link?
(A) DTE
(B) DCE
(C) HDLC
(D) PPP

Answer B.

Explanation

The DCE device controls the communication and should have the clock rate set.

Question 2.
Which of the following is the command you would use to set the clock rate on the DCE end of the link?
(A) R1#clock rate 64000
(B) R1(config)#clock rate 64000
(C) R1(config-if)#clock rate 64000
(D) R1>clock rate 64000

Answer C.

Explanation

R1(config-if)#clock rate 64000
In order to configure the clock rate, you would navigate to the serial interface that is
the DCE end of the link and use the clock rate command. The clock rate defines the speed of the link.

Question 3.
You are connecting a Cisco router to a WAN environment that uses routers from different vendors. What protocol should you use as the encapsulation protocol on the serial link?

(A) PPP
(B) HDLC
(C) PPTP
(D) L2TP

Answer A.

Explanation

If connecting a non-Cisco router, you will need to use PPP as the encapsulation protocol because it is a vendor-neutral protocol.

Question 4.
Which PPP authentication protocol uses a challenge/response algorithm to perform the authentication?
(A) PAP
(B) HDLC
(C) L2TP
(D) CHAP

Answer D.

Explanation

The Challenge Handshake Authentication Protocol (CHAP) securely transmits the authentication traffic by using a three-way handshake. It is more secure than PAP




Question 5.
Which of the following layer-2 protocols supports asynchronous communication and authentication?
(A) HDLC
(B) PPP
(C) PPTP
(D) SNMP
Answer B.

Explanation

PPP is a layer-2 protocol that is vendor-neutral, supports authentication, and is used on serial links as an asynchronous communication protocol.

Question 6.
Which of the following router port would you use to connect to a T1 line?
(A) AUI
(B) BRI
(C) Serial
(D) Console
(E) Fast Ethernet

Answer C.

Explanation

You would use a serial port to connect to an external CSU/DSU that would connect to the T1 line. T1 is one of the common types of digital data transmission systems used in telecommunications.  Originally developed by AT&T in the 1960s to support telephone service.
A T1 line is sort of a channel circuit delivering an internet connection directly from the broadband provider backbone.

Question 7.
Which PPP authentication protocol transfers username and passwords in clear text?
(A) CHAP
(B) MSCHAP
(C) PAP
(D) HDLC

Answer C.

Explanation

When configuring PPP authentication: PAP and CHAP,

PAP: Password authentication Protocol sends username and password in clear text.

CHAP: Challenge Handshake Authentication Protocol is a more secure procedure for connecting to a system . It encrypts the username and password

Question 8.
Which of the following are true in regard to PPP versus HDLC? (Select two.)
(A) HDLC only supports PAP authentication.
(B) PPP supports authentication.
(C) HDLC is vendor neutral.
(D) PPP is Cisco specific.
(E) PPP is vendor neutral.

Answer B. E

Explanation

PPP supports authentication. PPP is vendor neutral. PPP is an industry-standard serial link protocol that supports features such as compression and authentication.

Question 9.
Which of the following enables CHAP authentication and uses PAP authentication as a backup authentication method?
(A) authentication ppp chap pap
(B) ppp authentication chap backup pap
(C) authentication chap backup pap
(D) ppp authentication chap pap
Answer D.

Explanation

To enable PPP authentication, you use the PPP authentication command and then list the primary protocol and the secondary protocols to use.

 

Question 10.

You are looking to configure PPP authentication between two routers. What should you do? (Choose three.)
(A) Set the hostname on each router to the same name.
(B) Set the hostname on each router to a unique name.
(C) Create a username on each router named PPP.
(D) Create a username on each router that matches the hostname of the other router.
(E) Enable PPP authentication on both routers and specify CHAP as the authentication
protocol.
(F) Enable PPP authentication on the first router configured and specify either PAP or CHAP as the authentication protocol.

Answers

B. Set the hostname on each router to a unique name.
D. Create a username on each router that matches the hostname of the other router.
E. Enable PPP authentication on both routers and specify CHAP as the authentication protocol.

Explanation

To configure PPP authentication, you set the hostname on each router to a unique name and then create a username on each router that is the hostname of the other router. Ensure that the password for both usernames is the same value.

Then you enable PPP authentication and specify CHAP as the authentication protocol. CHAP is the more secure than PAP because it encrypts the username and password while PAP transmits usernames and passwords in clear text.



Question 11.

Which PPP sub-protocol is responsible for allowing PPP to support multiple network protocols?
(A) LCP
(B) NCP
(C) PPTP
(D) HDLC

Answer B.

Explanation

The NCP protocol allows PPP to function with different network protocols, such as IP or IPX.

Question 12.
Which of the following commands would you use to configure your router on a WAN that has non-Cisco routers as well?

(A)
R1(config-if)#ip address 165.45.1.1 255.255.255.252
R1(config-if)#encapsulation hdlc
R1(config-if)#no shutdown

(B)
R1(config-if)#ip address 165.45.1.1 255.255.255.252
R1(config-if)#encapsulation ppp
R1(config-if)#shutdown

(C)
R1(config-if)#ip address 165.45.1.1 255.255.255.252
R1(config-if)#encapsulation ppp
R1(config-if)#no shutdown

(D)
R1(config-if)#ip address 165.45.1.1 255.255.255.252
R1(config-if)#no shutdown
Answer C.

Explanation

R1(config-if)#ip address 165.45.1.1 255.255.255.252
R1(config-if)#encapsulation ppp
R1(config-if)#no shutdown
If connecting to non-Cisco devices, you need to use industry standard protocols. In this case, the encapsulation protocol on your serial link must be PPP.

Question 13.

PPP has a number of sub-protocols that perform different functions. Which protocol is responsible for negotiating authentication options?
(A) NCP
(B) LCP
(C) SNMP
(D) HDLC

Answer B.

PPP uses the Link Control Protocol (LCP) to negotiate settings such as compression, callback, multilink, and authentication.

Question 14.
Which of the following serial link protocols can implement multilink for load balancing?
(A) PPP
(B) HDLC
(C) L2TP
(D) PPTP

Answer A.

PPP is an industry-standard protocol used on serial ports that has features such as authentication, compression, multilink, and callback.

Question 15.

Which of the following are true in regards to WAN technologies? (Select three.)
(A) A router is typically considered a DCE device.
(B) A router is typically considered a DTE device.
(C) A modem is used to connect to an analog line.
(D) A CSU/DSU is used to connect to an analog line.
(E) A CSU/DSU is used to connect to a digital line.
(F) A modem is used to connect to a digital line.

Answer B. C E

B router is typically considered a DTE device.
C. A modem is used to connect to an analog line.
E. A CSU/DSU is used to connect to a digital line.
In most situations, your router is the DTE end of the communication link while the service provider is the DCE end of the WAN link.

CSU/DSU are used to connect to a digital network such as a leased line, while modems are used to connect to an analog network.