JNCIP-ENT EVPN Practice Question
An engineer is troubleshooting a newly configured EVPN-VXLAN multi-homed setup where the Designated Forwarder (DF) is constantly toggling between two PE routers. What is the most likely cause of this DF churn?
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
✓
Mismatched Ethernet Segment Identifiers (ESIs) or unstable BGP connectivity between PEs.
DF churn typically occurs when BGP sessions or reachability between the PE routers flapping, or when the timers (such as wait-for-timer) are misconfigured, causing conflicting DF election states.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Incorrect MAC mobility sequence numbers.
Why it's wrong here
MAC mobility sequence numbers handle host moves, not DF election stability.
- ✓
Mismatched Ethernet Segment Identifiers (ESIs) or unstable BGP connectivity between PEs.
Why this is correct
If ESIs match but BGP session stability or Type-4 route advertisements fluctuate, the DF election re-runs continuously, causing churn.
- ✗
Exceeding the maximum MAC address table limit.
Why it's wrong here
MAC limits restrict learning size, not DF election roles.
- ✗
Using VXLAN instead of MPLS data plane encapsulation.
Why it's wrong here
Encapsulation type does not dictate DF algorithm stability; DF is a control-plane function.
About these practice questions
One of 332 original JNCIP-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 JNCIP-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 JNCIP-ENT exam.