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300-410 Practice Question: An engineer configures mutual redistribution…
An engineer configures mutual redistribution between OSPF and EIGRP without route tagging. After convergence, some routes oscillate between the two protocols. What 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
✓
Routes redistributed from OSPF into EIGRP are re-redistributed back into OSPF, and the OSPF route is preferred over the original due to administrative distance, causing a loop.
Without route tagging, redistributed routes can be re-injected back into the original protocol, creating a routing loop. The administrative distance comparison can cause the route to be preferred from the wrong protocol, leading to oscillation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Routes redistributed from OSPF into EIGRP are re-redistributed back into OSPF, and the OSPF route is preferred over the original due to administrative distance, causing a loop.
Why this is correct
Without tagging, the router cannot distinguish between the original and redistributed route, leading to feedback loops.
- ✗
The seed metric for EIGRP is not set, so redistributed routes are dropped.
Why it's wrong here
Missing seed metric would cause routes to not be redistributed, not oscillation.
- ✗
OSPF has a higher administrative distance than EIGRP, so OSPF routes are always preferred.
Why it's wrong here
EIGRP has a lower AD (90) than OSPF (110), so EIGRP routes are preferred, but this does not cause oscillation.
- ✗
The 'redistribute ospf' command under EIGRP automatically sets a tag, preventing loops.
Why it's wrong here
Automatic tagging is not enabled by default; manual configuration is required.
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.