350-501 Question #629: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. OSPF is running in the given network. R1 was previously running EIGRP on a standalone network, and a network engineer just migrated it to OSPF. The R1 peering with R2 has come up. Which additional action must the engineer take so that R2 receives routes from Area 1 and Area 0 but is prevented from receiving routes from Area 2?

Options

• AImplement a route map that matches R2's interface to R3 and R4, and then attach the route map
• BImplement a route map that matches the routes in an ACL from Area 2, and then attach the route
• CImplement a route map that matches the routes from Area 2 in a prefix list, and then attach the
• DImplement a route map that matches R1's next-hop address, and then attach the route map to an

Explanation

To prevent R2 from receiving routes from Area 2 while allowing routes from Area 0 and Area 1, R1 must be configured with a route map that matches routes from Area 2 using an access control list and applies it as a distribute-list to R2.

Common mistakes.

• A. Implementing a route map that matches R2's interface to R3 and R4 is incorrect because filtering should be based on the routes themselves (their source area), not the interfaces R2 uses to reach other routers.
• C. While a prefix list could also be used to match routes from Area 2, an ACL is also a valid and common method, and this option does not specify where the route map would be attached or how it would filter.
• D. Implementing a route map that matches R1's next-hop address is incorrect because filtering needs to be based on the origin or attributes of the routes themselves, not R1's next-hop for those routes.

Concept tested. OSPF route filtering with route maps and ACLs

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/xe-16-12/iro-xe-16-12-book/iro-cfg-route-filtering.html

No community discussion yet for this question.