Cisco Certified Network Associate (CCNA) Practice Exam

An OSPF area that does not permit Type 7 LSA is known as what?

1. Stub area

2. Backbone area

3. Transit area

4. Normal area

The correct answer is: Backbone area

The correct answer is that an OSPF area that does not permit Type 7 LSA is known as a stub area. Stub areas are designed to limit the number of routes exchanged between OSPF areas, primarily to reduce the size of routing tables and improve stability within those areas. In the context of OSPF, Type 7 LSAs (Link-State Advertisements) are used in Not-So-Stubby Areas (NSSAs) to carry external route information into an OSPF domain. Stub areas, on the other hand, do not allow the introduction of external routes, limiting the types of LSAs they can receive to maintain simplicity and efficiency. They can only receive Type 1 LSAs (Router LSAs) and Type 2 LSAs (Network LSAs) from inside the area and Type 3 LSAs (Summary LSAs) from the backbone, but they completely exclude Type 7 LSAs. If an OSPF area is defined as a backbone area, it refers to Area 0, which is the central part of an OSPF network responsible for interconnecting all other areas. While backbone areas are critical, they do not have the same restrictions regarding LSA types as stub areas