JNCIS-ENT Tunnels Practice Question
Which TWO factors must be carefully managed when running OSPF over a GRE tunnel interface on Junos devices? (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
✓
Interface MTU settings to account for the additional GRE header size and prevent packet drops or fragmentation issues.
Running OSPF over GRE requires managing MTU/fragmentation to avoid dropped packets and configuring the OSPF network type appropriately (such as point-to-point) since GRE does not natively support broadcast or standard multi-access LAN semantics without special mapping.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Mandatory activation of BGP multipath routing on the physical transit interface.
Why it's wrong here
BGP multipath is unrelated to OSPF running inside a GRE tunnel.
- ✓
Interface MTU settings to account for the additional GRE header size and prevent packet drops or fragmentation issues.
Why this is correct
Account for the added GRE header by adjusting interface MTU or TCP MSS to prevent packet drops.
- ✗
Configuring MPLS Label Distribution Protocol (LDP) directly on the gr- interface.
Why it's wrong here
LDP is not run over standard GRE point-to-point IP tunnels in this manner.
- ✓
OSPF network type configuration (such as point-to-point) to ensure proper adjacency formation without requiring a designated router.
Why this is correct
Setting the OSPF network type to point-to-point avoids unnecessary DR/BDR election overhead across point-to-point GRE links.
- ✗
Enabling proprietary Junos Layer 2 bridging protocols over the gr- interface.
Why it's wrong here
GRE interfaces operate at Layer 3 and do not support Layer 2 bridging protocols directly.
Visual reference
About these practice questions
This JNCIS-ENT question is part of Courseiva's 519-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam 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.