Which of the following protocols uses a distance vector routing algorithm?

The protocol that utilizes a distance vector routing algorithm is RIP (Routing Information Protocol). Distance vector routing protocols determine the best path to a destination based on the distance to that destination, which is typically measured in hops. Each router maintains a routing table that contains the distances to all known destinations and shares this information with its directly connected neighbors.

RIP functions by using a simple algorithm that updates routers with the entire routing table at regular intervals, which can lead to slow convergence and potential routing loops. As a result, RIP is best suited for smaller networks where the overhead of periodic updates can be managed without significant performance issues.

In contrast, the other protocols listed operate using different methodologies. BGP (Border Gateway Protocol) uses a path vector protocol which focuses on the paths to reach a destination rather than simply counting hops. OSPF (Open Shortest Path First) is a link-state protocol that utilizes a more sophisticated method by building a complete map of the network's topology. IS-IS (Intermediate System to Intermediate System) is also a link-state protocol, similar to OSPF, which enables routers to exchange information about the state of their links to determine the best paths.