Which of the following algorithms is not a broadcast routing algorithm ?

Answer: Multidestination routing is not a broadcast routing algorithm.

• Flooding — forwards a packet out on all outgoing interfaces (except the incoming one) so every node receives the packet; this is a basic broadcast technique.

• Reverse path forwarding — used in broadcast and multicast to avoid loops by forwarding only if the packet arrived on the interface that lies on the shortest path back to the source.

• Multidestination routing — delivers packets to a specific set of destinations (a subset of nodes) rather than to all nodes; this selective delivery is not true broadcasting.

• All of the above — incorrect because flooding and reverse path forwarding are broadcast techniques, so it is not true that none of the listed algorithms are broadcast routing algorithms.

Key takeaway: Broadcast routing algorithms deliver packets to all nodes (flooding, reverse path forwarding), whereas multidestination routing targets a selected list of destinations and therefore is not a broadcast algorithm.