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300-410 Practice Question: Which THREE symptoms indicate that EIGRP is…
Which THREE symptoms indicate that EIGRP is experiencing a neighbor relationship issue due to an MTU mismatch? (Choose THREE.)
⚠ Common exam trap
Cisco often tests the distinction between symptoms of MTU mismatch (flapping, high retransmits, SIA) and symptoms of other EIGRP issues like active routes (DUAL query process) or hold time zero (hello failure), so candidates must associate MTU mismatch specifically with packet delivery failures rather than routing table states.
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 neighbor adjacency repeatedly goes up and down.
An MTU mismatch causes EIGRP packets to be fragmented or dropped, leading to repeated adjacency flaps as the neighbor relationship is re-established each time the hold timer expires. This instability is a classic symptom of MTU mismatch in EIGRP.
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 neighbor adjacency repeatedly goes up and down.
Why this is correct
MTU mismatch causes packet loss, leading to hold time expiration and neighbor resets.
- ✓
The 'show ip eigrp neighbors' command shows a high retransmission count (Retrans) for the neighbor.
Why this is correct
Retransmissions increase when EIGRP packets are dropped due to MTU issues.
- ✗
The 'show ip eigrp topology' command shows routes in active state.
Why it's wrong here
Active state in topology indicates a query process, not directly an MTU problem.
- ✓
The neighbor may become stuck-in-active (SIA) during route convergence.
Why this is correct
Packet loss from MTU mismatch can prevent query replies, leading to SIA.
- ✗
The 'show ip eigrp interfaces' command shows a hold time of zero.
Why it's wrong here
Hold time is a configured timer, not a dynamic value that drops to zero due to MTU issues.
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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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.