Cisco Certified Network Associate (CCNA) Practice Exam

Which LSA is generated by an ABR for each IPv6 subnet in a different area?

1. Type 1 LSA (Router LSA)

2. Type 2 LSA (Network LSA)

3. Type 3 LSA (Inter-Area Prefix LSA)

4. Type 4 LSA (ASBR Summary LSA)

The correct answer is: Type 3 LSA (Inter-Area Prefix LSA)

The Type 3 LSA, also known as the Inter-Area Prefix LSA, is generated by an Area Border Router (ABR) for each IPv6 subnet that lies in a different area. This LSA is crucial for providing routing information between different OSPF areas, enabling routers in one area to learn about the subnets that exist in another area. When an ABR creates a Type 3 LSA, it summarizes the routing information of the subnets in its area and advertises that summary into the backbone area (Area 0) or other areas. This ensures that routers in different areas can make informed routing decisions about how to reach those subnets. In contrast, a Type 1 LSA describes the router's links and its interfaces within a single area, a Type 2 LSA represents the network summary and includes information about the shared LAN segment, and a Type 4 LSA pertains to the information about ASBRs but does not apply to subnets in different areas like the Type 3 LSA does. Thus, the Type 3 LSA is specifically tasked with relaying prefix information across OSPF areas, which makes it the correct answer in the context of this question.