Which OSPF LSA type is sent by all routers in an area to advertise its connected subnets?

The type of OSPF LSA that is sent by all routers in an area to advertise its connected subnets is the router LSA. This is known as Type 1 LSA and is generated by each router to describe its interfaces, their states, and the networks they are connected to. It provides crucial information about the local topology within an OSPF area.

Each router creates its own Type 1 LSA to communicate information about the link state and to ensure that OSPF can efficiently create a complete and accurate representation of the network topology. These LSAs are then flooded throughout the area to allow all OSPF routers to synchronize their link state databases and compute the best paths for routing.

In contrast, network LSAs, which are generated by designated routers, describe the networks to which the OSPF routers are connected but do not advertise individual router connections. External and summary LSAs carry different types of routing information and are related to inter-area and external routing, rather than specific subnet information within an area, making them irrelevant for the goal of advertising interconnected subnets.