JNCIS-ENT: Juniper Networks Certified Specialist – Enterprise Routing and Switching (2025) — Question 52

You are an operator for a network running IS-IS. Two routers are failing to form an adjacency.
What are two reasons for this problem? (Choose two.)

Answer options

• A. There are mismatched router IDs on the L2 routers.
• B. There is no configured ISO address on any IS-IS interface.
• C. There is a mismatched area ID between the L2 routers.
• D. The family iso configuration is missing from the adjacency interface.

Correct answer: B, D

Explanation

The correct answers are B and D. An ISO address is essential for IS-IS interfaces, and if it is not configured, adjacency cannot be formed. Additionally, the family iso configuration must be present on the interface to establish the adjacency; without it, the routers cannot communicate properly. Options A and C are incorrect because mismatched router IDs and area IDs do not specifically prevent adjacency formation in this context.