OSPF Link State Advertisements (LSAs) are sent in which type of messages?

Link State Advertisements (LSAs) are crucial components of the OSPF (Open Shortest Path First) protocol, which is a link-state routing protocol used to facilitate routing decisions based on the state of the network's links. LSAs contain information about the routers, the networks they connect to, and links to those networks.

LSAs are specifically exchanged through Link State Update (LSU) messages. When an OSPF router discovers a change in the topology or is initializing, it sends out LSUs to inform neighboring routers of its LSAs. These LSUs encapsulate the LSAs and are responsible for sharing information about the state of links and the routers connected within the network.

The other message types listed serve different purposes within the OSPF process. Database Description (DBD) messages are used to summarize the content of the link-state database, while Link State Request (LSR) messages are sent by routers to request specific LSAs from their neighbors. Finally, LSAck messages are acknowledgments to confirm the receipt of LSAs. Each of these message types plays a role in the OSPF protocol but does not directly convey LSAs like the LSU does. Thus, the proper type of message for sending LS