Cisco Certified Network Associate (CCNA) Practice Exam

Which LSA type is generated by the DR in OSPF?

1. Type 1

2. Type 2

3. Type 3

4. Type 4

The correct answer is: Type 2

In OSPF (Open Shortest Path First), the Designated Router (DR) generates Type 2 Link-State Advertisements (LSAs). Type 2 LSAs, which are also known as Network LSAs, represent a multi-access network segment. This means that when multiple routers are connected to the same subnet, the DR takes on the responsibility of summarizing and advertising the link-state information of that segment. The reason the Type 2 LSA is specifically utilized is due to the way OSPF handles multi-access networks, such as Ethernet. The DR collects and consolidates the routing information from all routers in the broadcast domain, thereby reducing the amount of routing information that needs to be sent out and ensuring that only the DR floods this important information into the OSPF domain. Hence, by minimizing the LSA updates, the DR helps to optimize bandwidth utilization and reduce unnecessary processing on the routers in the network. Type 1 LSAs are generated by all routers and contain information about their own interfaces and directly connected neighbors, while Type 3 LSAs are used to summarize routes between areas. Type 4 LSAs provide information about ASBRs (Autonomous System Border Routers) in the network. However, none of these