Refer to the exhibit. A network administrator is troubleshooting a connectivity problem on the serial interfaces. The output from the show interfaces command on both routers shows that the serial interface is up, line protocol is down. Given the partial output for the show running-config in the exhibit, what is the most likely cause of this problem?
A. The serial cable is bad.
B. The MTU is incorrectly configured.
C. The Layer 2 framing is misconfigured.
D. The IP addresses are not in the same subnet.
From the output we see the Serial0/0 of RouterA is in “status up/protocol down” state which indicates a Layer 2 problem so the problem can be:
+ Keepalives mismatch
+ Encapsulation mismatch
+ Clocking problem