CCNP R&S Question of the Week: Routing Protocols into OSPF

March 27, 2015 Johnny Bass Cisco, Cloudera, Featured, Professional Development, Project Management, Routing & Switching, Technology, Training in Business

By default, which statement is correct regarding the redistribution of routes from another routing protocols into Open Shortest Path First (OSPF)? Select the best response.

A. They will appear in the OSPF routing table as type E2 routes.
B. All imported routes will be automatically summarized when possible, if not possible, OSPF will import the subnets.
C. They will appear in the OSPF routing table as type E1 routes.
D. Summarized routes are not accepted.
E. Only routes with lower administrative distances will be imported.

Reveal Answer

Answer: A.

When redistributing another protocol into OSPF, the default metric type is 2, meaning that the seed metric of 20 will be applied to the routes and all other routers in the OSPF domain will see it with that metric only. OSPF wants to auto-summarize the external routes before injecting them as LSA type 5, but if it is not possible, the routes are rejected and not automatically imported as subnets. The keyword ‘subnets’ must be added to stop the summarization of the external routes.

Related Resources
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Related Course
CCNP Routing and Switching e-Camp

CCNP R&S Question of the Week Series

CCNP R&S Question of the Week: IPv6
CCNP R&S Question of the Week: BGP Attribute
CCNP R&S Question of the Week: Gateway of Last Resort
CCNP R&S Question of the Week: Routing Protocols into OSPF

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