New CCNA PPP Common Questions.

By | August 14, 2017

Question 1
Which PPP subprotocol negotiates authentication options?

Answer: D

There are different PPP suite protocols, the single most important protocol is the PPP Link Control Protocol (LCP).
LCP is the chief controller protocol of PPP; it is responsible for its overall successful operation.
There are three main stages of “link life” and LCP plays a key role in each one:

Link Configuration: The process of setting up and negotiating the parameters of a link.

Link Maintenance: The process of managing an opened link.

Link Termination: The process of closing an existing link when it is no longer needed.

Question 2
As a network administrator you were asked to configure a serial link between the main office and a remote location. The router at the remote office is a non-Cisco router. How would you configure the serial interface of the main office router to make the connection?

A. Main(config)# interface serial 0/0
Main(config-if)# ip address
Main(config-if)# no shut

B. Main(config)# interface serial 0/0
Main(config-if)# ip address
Main(config-if)# encapsulation ppp
Main(config-if)# no shut

C. Main(config)# interface serial 0/0
Main(config-if)# ip address
Main(config-if)# encapsulation frame-relay
Main(config-if)# authentication chap
Main(config-if)# no shut

D. Main(config)# interface serial 0/0
Main(config-if)#ip address
Main(config-if)#encapsulation ietf
Main(config-if)# no shut

Answer: B

Question 3
Which two options are valid WAN connectivity methods? (Choose two)
D. L2TPv3
E. Ethernet

Answer: A C

Question 4
Which Layer 2 protocol encapsulation type supports synchronous and asynchronous circuits and has built-in security mechanisms?
C. X.25
D. Frame Relay

Answer: B
PPP supports both synchronous (like analog phone lines) and asynchronous circuits (such as ISDN or digital links). With synchronous circuits we need to use clock rate.
Note: Serial links can be synchronous or asynchronous. Asynchronous connections used to be only available on low-speed (<2MB) serial interfaces, but now, there are the new HWICs (High-Speed WAN Interface Cards) which also support asynchronous mode. To learn more about them please visit
Question 5
Which following command is used to enable CHAP authentication with PAP as the fallback method on a serial interface?
A. (config-if)# authentication ppp chap fallback ppp
B. (config-if)# authentication ppp chap pap
C. (config-if)# ppp authentication chap pap
D. (config-if)# ppp authentication chap fallback ppp

Answer: C
The command “ppp authentication chap pap” command indicates the CHAP authentication is used first. If it fails or is rejected by other side then uses PAP instead. If you want to use PAP first (then CHAP) you can use the “ppp authentication pap chap” command.

Question 6
Which of the following describes the roles of devices in a WAN? (Choose three.)
A. A CSU/DSU terminates a digital local loop
B. A modem terminates a digital local loop
C. A CSU/DSU terminates an analog local loop
D. A modem terminates an analog local loop
E. A router is commonly considered a DTE device
F. A router is commonly considered a DCE device

Answer: A D E

This is one of the fundamentals of networking.
The idea behind a WAN is to be able to connect two DTE networks together through a DCE network. The network’s DCE device (includes CSU/DSU) provides clocking to the DTE-connected interface (the router’s serial interface).


Question 7
Which two statements about using the CHAP authentication mechanism in a PPP link are true? (Choose two)
A. CHAP uses a two-way handshake.
B. CHAP uses a three-way handshake.
C. CHAP authentication periodically occurs after link establishment.
D. CHAP authentication passwords are sent in plaintext.
E. CHAP authentication is performed only upon link establishment.
F. CHAP has no protection from playback attacks.

Answer: B C

Question 8
Which of the following are key characteristics of PPP? (Choose three.)
A: can be used over analog circuits
B: maps Layer 2 to Layer 3 address
C: encapsulates several routed protocols
D: supports IP only
E: provides error correction

Answers: A C E

Question 9

What can a network administrator benefit by using PPP Layer 2 encapsulation? (Choose three.)
A: VLAN support
B: compression
C: authentication
D: sliding windows
E: multilink support
F: quality of service

Answers: B C E