Which one of the following statements regarding totally stub areas in OSPF is true?

Totally stub areas in OSPF (Open Shortest Path First) are designed to limit the types of routing information that can be propagated into and out of the area. The key feature of totally stub areas is that they do not receive Type 5 LSAs, which carry external route information. Instead, they rely on a default route for reaching external networks.

When examining the role of Type 3 LSAs, which convey inter-area route information, totally stub areas do not accept these either. Therefore, by definition, a totally stub area does not allow Type 3 default routes, making this statement accurate.

To understand why the other statements are not correct:

• Allowing AS external routes and inter-area routes negates the primary purpose of a totally stub area, which is to minimize routing information and control the complexity within the area.

• Stating that totally stub areas allow intra-area routes and Type 3 default routes is also incorrect, as totally stub areas do not process Type 3 LSAs at all, relying solely on the default route for external connectivity.

• The mention of allowing external AS routes through Type 7 LSAs misrepresents the functionality of totally stub areas; they do not support Type 7 LSAs