Which multicast routing protocol operates on a distance vector basis?

The correct answer is DVMRP, which stands for Distance Vector Multicast Routing Protocol. This protocol uses a distance vector routing methodology, similar to what is seen in traditional unicast distance vector protocols like RIP. In DVMRP, routers exchange multicast routing information in the form of distance vectors, allowing them to build a distribution tree for multicast traffic based on the shortest path metrics. The protocol is specifically designed for the efficient delivery of multicast traffic within an Internet Protocol (IP) environment and operates by maintaining a forwarding table that contains the paths to each multicast group.

DVMRP employs the principles of distance vector routing to manage the multicast group memberships and the paths taken to each group, which makes it uniquely suited for scenarios where multicast traffic needs to be routed across various nodes in a network. This method allows DVMRP to propagate multicast data effectively, leveraging the familiar distance vector routing concepts of next hop and metric calculation.

In contrast, the other protocols listed either operate on different mechanisms or are used for different types of routing. MOSPF, for instance, is a link-state protocol, while PIM can operate in both sparse and dense modes but is not based on distance vector principles. RIP, although it is a distance vector protocol, is used for