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352-001 · Question #667
352-001 Question #667: Real Exam Question with Answer & Explanation
The correct answer is A: distribute lists. Distribute lists filter specific prefixes at redistribution points between OSPF and EIGRP, blocking routes from re-entering their origin domain and breaking redistribution loops with straightforward configuration.
Question
You are asked to provide a design that allows full dynamic routing updates between two networks: one network runs OSPF, and the other network runs EIGRP. Two links with an EIGRP neighbor relationship are provided to connect the networks and exchange routes. You are considering the use of routing loops. Which route-filtering method should you recommend, in order to prevent loops with the least amount of reconfiguration effort?
Options
- Adistribute lists
- Boffset lists
- Croute filtering
- Droute tagging
Explanation
Distribute lists filter specific prefixes at redistribution points between OSPF and EIGRP, blocking routes from re-entering their origin domain and breaking redistribution loops with straightforward configuration.
Common mistakes.
- B. Offset lists adjust EIGRP or RIP metrics for routes in or out of an interface but do not block route redistribution; routes with modified metrics can still be redistributed back into their origin domain and cause loops.
- C. Route filtering is a generic term describing the broad category of filtering techniques and does not identify a specific, implementable method for preventing redistribution loops.
- D. Route tagging marks redistributed routes with a numeric tag and then denies those tags on re-entry into the source domain, which is effective but requires modifying route maps on multiple routers and adding tag-match conditions, resulting in more reconfiguration effort than distribute lists.
Concept tested. Distribute lists preventing redistribution routing loops
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