Cisco Enterprise Network Core Technologies (ENCOR) Practice Exam

The LSA (Link State Advertisement) Sequence Number serves a critical function within OSPF (Open Shortest Path First) routing protocols. It is specifically designed to provide a mechanism for tracking changes to the link state information over time. Each time a router generates and sends out an update in the form of an LSA, it increments the sequence number associated with that LSA. This incrementing of the sequence number serves as a versioning system, enabling other routers in the network to determine whether they have the most current information regarding the state of the links.

When routers receive LSAs, they compare the sequence numbers of the incoming LSAs to those they already have in their database. Should the incoming LSA possess a higher sequence number, it indicates that this information is more recent, prompting the receiving router to update its link state database and propagate the new information onwards. Thus, the LSA Sequence Number is crucial for maintaining consistency and ensuring that all routers have the latest network topology information.

In contrast, the other options highlight different aspects of OSPF LSAs that do not directly relate to the purpose of the Sequence Number. Identifying the originating router pertains to the LSA itself but is not about the sequence number. Designating the type of