JNCIP-ENT: Juniper Networks Certified Professional – Enterprise Routing (2023) — Question 19

Which two statements are true about IS-IS levels? (Choose two.)

Answer options

• A. Level 1 systems use a default route to reach AS external routes located in other areas.
• B. Level 2 systems must use the loopback address as a part of the ISO network address.
• C. Level 1 systems only from adjacencies with other systems that have different area IDs.
• D. Level 2 systems do not advertise Level 2 routes into a Level 1 area by default.

Correct answer: A, D

Explanation

Option A is correct because Level 1 systems indeed use a default route to reach external routes in different areas. Option D is also correct because Level 2 systems do not by default advertise Level 2 routes into Level 1 areas. Options B and C are incorrect as they do not accurately describe the behaviors of Level 2 and Level 1 systems regarding area IDs and addresses.