You are configuring an IS-IS IGP network and do not see the IS-IS adjacencies established. In this scenario, what are two reasons for this problem? (Choose two.)

You are configuring an IS-IS IGP network and do not see the IS-IS adjacencies established. In this scenario, what are two reasons for this problem? (Choose two.)
A . MTU is not at least 1492 bytes.
B . IP subnets are not a /30 address.
C . The Level 2 routers have mismatched areas.
D . The lo0 interface is not included as an IS-IS interface.

View Answer

Answer: AD

Explanation:

Option A suggests that the MTU is not at least 1492 bytes. This is correct because IS-IS requires a minimum MTU of 1492 bytes to establish adjacencies1. If the MTU is less than this, IS-IS adjacencies will not be established1.

Option D suggests that the lo0 interface is not included as an IS-IS interface. This is also correct because the loopback interface (lo0) is typically used as the router ID in IS-IS1. If the loopback interface is not included in IS-IS, it could prevent IS-IS adjacencies from being established1. Therefore, options A and D are correct.