Link-state routing protocols compute shortest paths using which algorithm?

• A. Dijkstra's
• B. Bellman-Ford
• C. Floyd-Warshall
• D. Prim

Answer: (A)

Link-state routing protocols build a complete view of the network and then determine routes by a single-source shortest-path calculation on that graph. Dijkstra's algorithm fits this approach because it efficiently computes the minimum-cost path from the origin to every other node in a graph with non-negative link costs, giving the exact routes that a router uses to populate its forwarding table. Bellman-Ford is associated with distance-vector routing and can handle certain anomalies, but it’s slower and can be less scalable for larger networks. Floyd-Warshall finds shortest paths between all pairs of nodes, which is more than a single-router needs and isn’t how a router computes its own next hops. Prim, on the other hand, finds a minimum spanning tree, which isn’t about selecting the best routes to destinations. With link-state, applying Dijkstra's algorithm ensures consistent, optimal routing across the network.