JNCIS-ENT IS IS Practice Question
Which TWO characteristics describe the behavior and properties of Level 1 and Level 2 routing in IS-IS? (Choose two)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Level 2 routers form the backbone and can route traffic between different IS-IS areas.
Level 1 areas are responsible for intra-area routing, similar to OSPF non-backbone areas. Level 2 routers form the backbone network and route between different areas.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Level 1 routers are strictly prohibited from connecting to Level 2 routers under any circumstances.
Why it's wrong here
Level 1/2 routers bridge Level 1 and Level 2 domains seamlessly.
- ✗
Level 1 routing requires the explicit configuration of a designated Area 0 backbone.
Why it's wrong here
IS-IS does not have an explicit Area 0 backbone concept like OSPF; Level 2 forms the contiguous backbone.
- ✓
Level 2 routers form the backbone and can route traffic between different IS-IS areas.
Why this is correct
Level 2 routing constitutes the backbone, connecting different areas together.
- ✗
Level 2 routers do not support wide metrics and only operate with narrow metrics.
Why it's wrong here
Level 2 routing fully supports wide metrics just like Level 1.
- ✓
Level 1 areas use intra-area routing and require all routers within the same area to share a common area address.
Why this is correct
Level 1 routers must share at least one common area address to form intra-area adjacencies.
Visual reference
About these practice questions
Courseiva writes every JNCIS-ENT question from scratch — 519 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Juniper Networks exam blueprint
This JNCIS-ENT practice question is part of Courseiva's free Juniper Networks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the JNCIS-ENT exam.