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300-410 Practice Question: An engineer configures OSPFv2 on two routers with…
An engineer configures OSPFv2 on two routers with a direct Ethernet link. The routers are stuck in the EXSTART state. Which is the most likely explanation?
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
✓
The interface MTU on one router is 1500, and on the other is 1400.
OSPF neighbors can become stuck in EXSTART when there is a mismatch in the interface MTU. The DBD packet size is based on the interface MTU; if the receiving interface has a smaller MTU, the DBD packet is dropped, preventing the adjacency from progressing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The interface MTU on one router is 1500, and on the other is 1400.
Why this is correct
An MTU mismatch causes DBD packets to be dropped, stalling the adjacency in EXSTART.
- ✗
The OSPF hello and dead intervals are mismatched.
Why it's wrong here
Mismatched hello/dead intervals prevent the adjacency from forming at all, not getting stuck in EXSTART.
- ✗
One router has OSPF authentication configured, and the other does not.
Why it's wrong here
Authentication mismatch prevents neighbor state progression past INIT or 2-WAY, not EXSTART.
- ✗
The OSPF network type is point-to-point on one router and broadcast on the other.
Why it's wrong here
Network type mismatch typically prevents adjacency or causes it to stall at INIT, not EXSTART.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 practice question is part of Courseiva's free Cisco 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 300-410 exam.