What triggers the flooding of LSAs within an OSPF network?

The flooding of Link State Advertisements (LSAs) within an OSPF network is primarily triggered by changes in the network topology. OSPF, or Open Shortest Path First, is a link-state routing protocol that relies on LSAs to share the state of network links among routers.

When there is a change in the network, such as the addition or removal of a router, changes in link cost, or a failure of a link, routers detect these changes and generate LSAs to inform other routers about the current state of the network. Once an LSA is generated, it is flooded to all adjacent routers, ensuring that all routers have the most up-to-date view of the network topology. As a result, they can calculate the most efficient routes for data transmission.

Other options are less relevant in the context of OSPF. The completion of the routing table is not a direct trigger; rather, it is the purpose of OSPF operation. Periodic timer expirations, while they can lead to the transmission of certain types of LSAs, are not the primary cause of flooding, which is about reacting to network changes. Manual intervention by the administrator can also cause changes but is not a routine trigger for LSA flooding like