What are three common characteristics of OSPF and IS-IS?

The selection highlights a significant characteristic shared by both OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System): the election of a designated router (DR) and a backup designated router (BDR) on broadcast and multi-access networks. This feature is crucial for efficient network operation, as it minimizes the amount of OSPF or IS-IS routing traffic on a shared LAN segment. By designating a DR and BDR, these protocols can reduce the number of adjacencies that need to be established, thus optimizing the way routing information is exchanged among routers on the network. This election process ensures a singular point for distributing routing updates, thereby alleviating the possibility of routing loops and ensuring quicker convergence times.

The other choices do not accurately reflect shared characteristics of OSPF and IS-IS. While both protocols utilize a link-state database for routing decisions, it is important to note that they differ in how they implement and maintain these databases. Furthermore, the link-state protocols do not use variable hop counts, as they are not distance-vector protocols; instead, they depend on the state of the links, not the number of hops. Lastly, while manual configuration occurs, particularly in policy application or specific network designs