JNCIS-ENT High Availability Practice Question
You are troubleshooting a BGP session failure immediately following a manual Routing Engine switchover on an MX series router configured with GRES and NSR. BGP drops its peering session. What is the most likely reason for the failure?
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
✓
NSR was not enabled under the BGP routing-options protocol hierarchy, causing the protocol daemon state to not synchronize to the backup Routing Engine.
If NSR is enabled, protocol state is synced, but if Graceful Restart is misconfigured or helper mode is disabled on the peer, or if backup sync failed, state could be lost.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
NSR was not enabled under the BGP routing-options protocol hierarchy, causing the protocol daemon state to not synchronize to the backup Routing Engine.
Why this is correct
While GRES preserves the forwarding plane, NSR must be explicitly enabled for specific protocols (like BGP or OSPF) to sync control plane states.
- ✗
The Virtual Chassis stacking cable was disconnected during the switchover.
Why it's wrong here
MX series routers use redundant Routing Engines in a modular chassis, not Virtual Chassis stacking cables.
- ✗
VRRP preemption caused the default gateway IP to shift to the backup engine.
Why it's wrong here
VRRP operates at Layer 3 on interfaces and is independent of BGP daemon state synchronization.
- ✗
The LACP timeout on the aggregated uplink was set to slow mode.
Why it's wrong here
LACP timeout does not affect BGP routing engine switchover states.
Visual reference
About these practice questions
One of 519 original JNCIS-ENT practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. 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.