Differentiate between distance-vector and link-state routing protocols with an example each.

• A. Distance-vector shares routing info with neighbors periodically (e.g., RIP); Link-state builds a complete topology map and floods it (e.g., OSPF).
• B. Distance-vector floods topology; Link-state shares routing table periodically.
• C. Distance-vector uses LSAs; Link-state uses distance vector updates.
• D. Distance-vector routing doesn't use metrics.

Answer: (A)

The difference lies in how routing information is shared and how the network is mapped to compute routes. In distance-vector routing, each router periodically shares its routing table with its directly connected neighbors, and relies on information from those neighbors to learn about distant networks. An example is RIP, which uses hop count as its metric and sends updates to neighbors at regular intervals. In link-state routing, every router creates a complete map of the network by flooding link-state advertisements with topology information to all routers in the area, so each router can independently compute the best paths using a shortest-path algorithm like Dijkstra. An example is OSPF, which builds a full topology database and uses LSAs to distribute it.

The given description correctly identifies these two behaviors: distance-vector shares routing info with neighbors periodically (e.g., RIP), while link-state builds a complete topology map and floods it (e.g., OSPF). Other statements are inaccurate because they reverse the roles (flooding topology is a link-state action, not distance-vector) or claim that distance-vector uses LSAs or that it doesn’t use metrics, which is not true since distance-vector uses metrics like hop count.