Cisco Certified Network Associate (CCNA) Practice Exam

Which command configuration designates an area as a not so stubby area (NSSA)?

1. (config-router)#area AREA NUMBER stub

2. (config-router)#area AREA NUMBER nssa

3. (config-router)#area AREA NUMBER totally-stubby

4. (config-router)#area AREA NUMBER no-summary

The correct answer is: (config-router)#area AREA NUMBER nssa

The command that designates an area as a not so stubby area (NSSA) is indeed the one that uses the designation "nssa." In OSPF (Open Shortest Path First), an NSSA allows routes from external sources to be imported while still maintaining some of the characteristics of a stub area. This is important for scenarios where external routing information needs to be shared within a restricted scope without allowing all routing information, thereby optimizing routing table size and efficiency. Stub areas prevent external routes from being propagated into them, and the NSSA offers a middle ground by allowing a specific type of external route, making it a valuable option in certain network designs. By using the "nssa" command, you ensure that the area can accept external routes without losing all the benefits of operating as a stub. This command effectively influences how OSPF behaves with respect to external route advertisements in that specific area, allowing for greater flexibility in OSPF network design while controlling routing information flow.