Refer to the Exhibit.

R1 and R2 are directly connected using the interfaces shown in the exhibit. R1 can ping R2’s
interface, and R2 can ping R1’s interface. The IS-IS adjacency will not come up. What is causing
the adjacency to fail?

A.
The correct levels are not configured under protocols isis.

B.
The link MTU is too small to support IS-IS.

C.
Authentication is not properly configured for the adjacency.

D.
Both routers are configured as the DR, causing a conflict.

Explanation: