GATE CS 2025 Set 2 | Question 17

MCQ · 1 mark · −0.33

Consider the routing protocols given in List I and the names given in List II:

List IList II
(i) Distance vector routing(a) Bellman-Ford
(ii) Link state routing(b) Dijkstra

For matching of items in List I with those in List II, which ONE of the following options is CORRECT?

  1. Option A: (i) – (a) and (ii) – (b) (correct)
  2. Option B: (i) – (a) and (ii) – (a)
  3. Option C: (i) – (b) and (ii) – (a)
  4. Option D: (i) – (b) and (ii) – (b)

Answer

(A)

Explanation

In distance vector routing (used by RIP), a router learns only the distance vectors of its neighbours. It keeps improving its own estimates with the Bellman-Ford relation \(D_x(y) = \min_v \{c(x, v) + D_v(y)\}\): the cost to a neighbour \(v\) plus that neighbour's distance to \(y\). So (i) matches (a).

In link state routing (used by OSPF), every router floods the costs of its own links, so each router learns the whole topology and runs Dijkstra's shortest path algorithm from itself. So (ii) matches (b).

The other options pair at least one protocol family with the wrong algorithm.

Answer: A