Which OSPF LSA type has a domain flooding scope?

The correct answer is that the external LSA (Link State Advertisement) type in OSPF has a domain flooding scope. External LSAs are used to advertise routes that originate from outside the OSPF area. This typically includes routes from other routing protocols, such as RIP or BGP, and they carry information about external networks.

External LSAs are flooded throughout the entire OSPF Autonomous System (AS), which is why they are said to have a domain flooding scope. This domain scope allows OSPF to fully integrate external routing information into its internal routing tables. The external LSAs come in two flavors: Type 1 (E1) and Type 2 (E2), with E1 LSAs considering both the cost of the external path and the cost to reach the ASBR (Autonomous System Border Router), while E2 LSAs only consider the cost to reach the external network. This capability of OSPF to incorporate external routes is crucial for scalable internetworking.

Other types of LSAs, such as router, network, and summary, are used within OSPF areas to manage internal routing information. Their flooding scope is limited to either specific OSPF areas or, in the case of summary LSAs,