Cisco Certified Network Associate (CCNA) Practice Exam 2025 - Free CCNA Practice Questions and Study Guide

A totally stubby area in OSPF (Open Shortest Path First) is designed to simplify routing within the area by blocking certain types of Link State Advertisements (LSAs). Specifically, it prevents type 3, type 4, and type 5 LSAs from being flooded into the area.

Type 3 LSAs are used to describe inter-area routes (routes to other OSPF areas), while type 4 LSAs provide information about autonomous system boundary routers (ASBRs) to enable routing to external networks. Type 5 LSAs are utilized to advertise external routes from outside the OSPF domain. By blocking these types of LSAs, a totally stubby area reduces the size of the OSPF routing table and improves convergence time, as routers within the totally stubby area only need to be aware of internal routes and a default route to reach external destinations.

In this context, the correct answer reflects the specific types of LSAs that are not allowed into a totally stubby area, which contributes to the overall efficiency and manageability of the OSPF network.