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

The correct answer highlights that both OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System) share common characteristics in their operational framework. Specifically, both protocols utilize a link-state database that is constructed based on the Dijkstra shortest path first algorithm. This foundational feature allows for the computation of the shortest paths within a network, enabling efficient routing decisions.

Employing the Dijkstra algorithm means that both protocols assess the entire topology of the network rather than relying on the routes shared from neighboring routers. As each router independently builds a complete map of the network, it can make intelligent decisions based on overall network conditions instead of just local information. This enhances the convergence time and stability of the network, as any changes in the topology can be quickly propagated and reflected in the routing decisions made by the routers.

While other options address valid functions and features of these protocols, they don't accurately capture this fundamental characteristic that is shared by both OSPF and IS-IS. This makes the choice that refers to the link-state database and the algorithm utilized the most accurate representation of their common operational principles.