CISCO CCNA 200-301 Q140

Your assistant has been assigned the task of configuring one end of a WAN link between two offices. The link is a serial connection and the router on the other end is a non-Cisco router. The router in the other office has an IP address of The connection will not come up, so you ask your assistant to show you the commands he configured on the Cisco router. The commands he executed are shown below.

Ciscorouter(config)# interface serial0/0
Ciscorouter(config-if)# ip address
Ciscorouter(config-if)# no shut

What command(s) should he run to correct the configuration?

Ciscorouter(config-if)# no ip address
Ciscorouter(config-if)# ip address

B. Ciscorouter(config-if)# encapsulation ppp

C. Ciscorouter(config-if)# encapsulation ansi

D. Ciscorouter(config-if)# authentication chap

Correct Answer: B

There are three encapsulation types available for a serial connection: High-Level Data Link Control (HDLC), Point-To-Point (PPP), and Frame Relay.

HDLC is the default on Cisco routers and the form of HDLC used on a Cisco router is incompatible with routers from other vendors. Since the encapsulation command was not run, the router is set for HDLC. To correct this, you should execute the encapsulation ppp command. Frame Relay could also be used if the other router were running Frame Relay, since it also is an industry standard.

The IP address does not need to be changed. It is currently set for This is correct since it is in the same subnet as the IP address of the other end,

The command authentication chap should not be run because the scenario does not indicate that authentication is configured on the other end. If it is set on one end, it must be set on the other as well.

The command encapsulation ansi should not be run because ANSI is not an encapsulation type. It is an LMI type used in Frame Relay. The three LMI options available are Cisco, ANSI, and ITU.