
Refer to the exhibit. A network operator is attempting to configure an IS-IS adjacency between two routers, but the adjacency cannot be established. To troubleshoot the problem, the operator collects this debugging output. Which interfaces are misconfigured on these routers?
Correct Answer: A
The debugging output indicates an issue with IS-IS level configuration on interfaces attempting to form an adjacency. For IS-IS adjacencies to form correctly, both interfaces must operate at the same level or be configured to support multi-level (Level-1-2). If one router's interface is set to Level 1 only while another's is set to Level 2 only, they will not form an adjacency because they are operating at different levels of the IS-IS hierarchy. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.1