Which routing protocol utilizes a distance-vector methodology?

The choice of the routing protocol that utilizes a distance-vector methodology is based on how routes are calculated and shared between routers. In the case of RIP (Routing Information Protocol), it employs a straightforward distance-vector approach where routers periodically share their routing tables with neighboring routers. The term "distance vector" refers to the fact that each router sends a vector of distances (i.e., the number of hops to reach different networks) to its neighbors.

Distance-vector protocols operate by having routers share their knowledge of the whole network with immediate neighbors, allowing them to learn about the reachability of other networks indirectly over a series of hops. RIP uses a maximum hop count of 15, which limits its use in larger networks, but this method makes it simple and easy to implement.

In contrast, other protocols mentioned, such as OSPF (Open Shortest Path First), utilize a link-state methodology, while EIGRP (Enhanced Interior Gateway Routing Protocol) is classified as a hybrid protocol that combines features from both distance-vector and link-state protocols. BGP (Border Gateway Protocol) operates differently as a path vector protocol, focusing on the policies of how routes are chosen between autonomous systems rather than just distance.