Which of the following protocols is classified as a distance vector routing protocol?

RIP, or Routing Information Protocol, is classified as a distance vector routing protocol because it uses a straightforward approach to determine the best path for data packets to travel across a network. Distance vector protocols operate by having each router share its routing table with its immediate neighbors, along with the distance, typically measured in hop count, to each of the destinations.

In RIP's case, it maintains a maximum hop count of 15, meaning if a destination is more than 15 hops away, it is considered unreachable. The protocol relies on periodic updates to communicate changes in the routing tables, which are sent to all neighboring routers, allowing the routers to build and maintain their routing tables based on the information received. This simplicity, combined with the limitations on hop count and reliance on neighbor notifications, distinctly categorizes RIP as a distance vector routing protocol.

In contrast, OSPF (Open Shortest Path First) is a link-state routing protocol, which builds a complete map of the network topology, allowing for more efficient routing decisions. EIGRP (Enhanced Interior Gateway Routing Protocol) is classified as a hybrid protocol, having features of both distance vector and link-state protocols. ISIS (Intermediate System to Intermediate System) is also a link-state routing protocol.