JNCIP-ENT IP Multicast Practice Question
An administrator configures MSDP peering between two routers. After configuration, the MSDP session remains in the 'Connect' or 'Active' state and never transitions to 'Established'. Which underlying protocol dependency must be verified and operational for MSDP sessions to establish?
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
✓
TCP connectivity on port 639 between the MSDP peers
MSDP relies directly on TCP (TCP port 639) to establish peer connections. If TCP connectivity fails, the MSDP state will not reach Established.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
TCP connectivity on port 639 between the MSDP peers
Why this is correct
MSDP runs over TCP using port 639; if TCP fails, the session cannot reach the Established state.
- ✗
MBGP unicast routing tables synchronized
Why it's wrong here
MBGP is used for RPF checks, but the direct peer handshake relies on TCP.
- ✗
PIM dense-mode adjacency between the peers
Why it's wrong here
MSDP does not require PIM dense-mode between peers.
- ✗
IGMPv3 snooping enabled on intermediate switches
Why it's wrong here
IGMP snooping is a layer 2 feature and is not required for MSDP TCP sessions.
Visual reference
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.