Which type of OSPF area restricts external routes from other areas but allows external routes to be flooded by ASBRs within its own area?

Which type of OSPF area restricts external routes from other areas but allows external routes to be flooded by ASBRs within its own area?

Which type of OSPF area restricts external routes from other areas but allows external routes to be flooded by ASBRs within its own area?

A.
not-so-stubby area

B.
backbone area

C.
stub area with no-summaries configured

D.
stub area

Explanation:
* Configure a not-so-stubby area (NSSA). An NSSA allows external routes to be flooded within the area. These routes are then leaked into other areas.
* You cannot configure an area as being both a stub area and an NSSA.
* The remaining statements are explained separately.

The NSSA Option for OSPF areas is defined in RFC 1587. The NSSA option partially undoes a portion of what the stub area is designed to do. The OSPF stub area eliminates the propagation of external routes in an area by creating a default route that is propagated into the NSSA by the ABR. The NSSA standard creates a new type of LSA, the type 7 (NSSA External) LSA, and floods that through the NSSA. ABRs for the NSSA translate type 7 LSAs and propagate them to the backbone area and other type-5-LSA capable areas as type 5 (external) LSAs. ASBRs in the NSSA are not actually advertised into the backbone area as type 4 (ASBR summary) LSAs.



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