David is trying to fix a connectivity issue between two routers that are directly connected through the serial line. The serial line is up, but he cannot see any neighbors displayed when he runs the show cdp neighbors command. Which of the following layers could be a part of this problem?
A)Data link
B)Physical
C)Network layer
D)Transport layer

Question

Quizplus · Accepted Answer

If the serial line is up and he cannot see any neighbors when he runs the show cdp command, it means that the problem is with the data link layer.
Key Takeaway: The show cdp neighbors command displays detailed information about neighboring devices discovered using Cisco Discovery Protocol. CDP runs over the data link layer and is used to show information about the interfaces your router uses. Hence, if CDP does not work, it is a problem associated with the data link layer.

David Is Trying to Fix a Connectivity Issue Between Two