350-501 Networking Practice Question
During a network migration from EIGRP to OSPF, you notice that some routes are being redistributed incorrectly, causing routing loops. The OSPF domain uses area 0 and area 1. The EIGRP domain uses AS 100. Which configuration change would best prevent loops during the migration?
⚠ Common exam trap
Cisco often tests the misconception that simply adjusting administrative distance or using stub areas can prevent redistribution loops, when in fact only explicit tagging and filtering (or route-map-based control) can break the two-way redistribution cycle.
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
✓
Use route-maps to tag EIGRP routes and filter them on OSPF routers.
Route-maps allow you to tag redistributed EIGRP routes with a specific tag value (e.g., 'tag 100') and then filter those tagged routes on OSPF routers using a distribute-list in or prefix-list combined with the route-map. This prevents the redistributed routes from being re-injected back into EIGRP, breaking the redistribution loop. Without such tagging and filtering, mutual redistribution between EIGRP and OSPF can cause routing loops due to the two-way redistribution of routes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Implement OSPF stub areas to limit external routes.
Why it's wrong here
Stub areas limit external LSAs but do not prevent redistribution loops.
- ✓
Use route-maps to tag EIGRP routes and filter them on OSPF routers.
Why this is correct
Tags allow conditional redistribution filtering, preventing routes from being sent back to EIGRP.
- ✗
Use distribute-list in EIGRP to block OSPF routes.
Why it's wrong here
While this can prevent loops, route-maps with tags are more granular and a best practice.
- ✗
Set a high administrative distance on redistributed routes in OSPF.
Why it's wrong here
Changing AD might cause preference issues but does not prevent loops.
Visual reference
Go deeper
Related to this question
About these practice questions
Courseiva writes every 350-501 question from scratch — 971 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-501 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 350-501 exam.