hardMultiple ChoiceObjective-mapped
300-410 Practice Question: An engineer configures mutual redistribution…
An engineer configures mutual redistribution between OSPF and EIGRP on a router. After a few minutes, the router's CPU spikes and routes start flapping. Which is the most likely explanation?
⚠ Common exam trap
Cisco often tests the concept that mutual redistribution inherently causes loops unless explicit filtering or tagging is applied, and candidates mistakenly focus on missing metrics or administrative distance instead of the re-redirection loop.
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 redistribution is creating a routing loop because there is no route tagging or filtering to prevent re-redistribution.
Mutual redistribution without route tagging or filtering causes the redistributed routes to be re-injected back into the original routing protocol, creating a routing loop. This loop leads to continuous route updates, CPU spikes, and route flapping as the router repeatedly processes and advertises the same prefixes.
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 redistribution is creating a routing loop because there is no route tagging or filtering to prevent re-redistribution.
Why this is correct
Correct. Without tagging, routes can loop between protocols.
- ✗
The seed metric is not configured, so the routes are not redistributed.
Why it's wrong here
Missing seed metric would prevent redistribution, not cause flapping.
- ✗
The administrative distance is set too low, causing the router to prefer the wrong route.
Why it's wrong here
AD mismatch could cause issues but not necessarily loops.
- ✗
The OSPF process ID is the same on both routers.
Why it's wrong here
Process ID is local; same ID does not cause loops.
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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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.