A router running a distance-vector protocol learns from its neighbor that a destination is 3 hops away. What distance does the router record for that destination in its own routing table?
A3 hops, identical to the neighbor's distance
B4 hops, adding 1 for the link to the neighbor
C1 hop, since the neighbor is one step away
DThe router queries the destination directly to find the true distance
In distance-vector routing, a router adds 1 (the cost of reaching its neighbor) to the neighbor's advertised distance. If the neighbor says the destination is 3 hops, the route through that neighbor costs 3 + 1 = 4 hops. This additive logic is the 'distance vector' — each router only knows distances, not the full path.
Question 2 True / False
Link-state routing protocols are slower to converge than distance-vector protocols because they flood more information across the network.
TTrue
FFalse
Answer: False
Despite the higher overhead of flooding, link-state protocols (like OSPF) converge faster. Each router builds a complete, accurate map of the network and computes optimal paths independently. Distance-vector protocols are prone to slow convergence — especially the 'count-to-infinity' problem — because routers only know their neighbors' distances and may cycle through incorrect routes before settling.
Question 3 Short Answer
What is the fundamental difference between the information a distance-vector router shares with its neighbors and the information a link-state router floods to all routers?
Think about your answer, then reveal below.
Model answer: A distance-vector router shares its routing table — a list of destinations and the distances to them. A link-state router shares its link-state advertisements (LSAs) — a description of its directly connected links and their costs, not the full routing table.
This distinction is the key conceptual divide. Distance-vector routers share their computed conclusions (how far away things seem). Link-state routers share raw facts about their local environment (what links they have). Every link-state router then independently reconstructs the full topology and computes shortest paths using Dijkstra's algorithm, rather than trusting its neighbors' potentially stale conclusions.