Which algorithm does OSPF use to compute the shortest path?

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

Answer: (A)

OSPF computes shortest paths using Dijkstra's algorithm. After routers flood link-state advertisements to build a complete topology map with link costs, each router treats that map as a graph and runs Dijkstra's algorithm from itself to determine the shortest-path tree to every destination. The routing table is then filled by following the next hop along that tree, ensuring each route follows the least-cost path. The other options describe different problems or protocols: Bellman-Ford is used in distance-vector routing like RIP, Floyd-Warshall finds all-pairs shortest paths (more of a theoretical/all-at-once approach), and Prim's finds a minimum spanning tree (not used for routing decisions).