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GATE 2010 CS (CS1) – Question 64

Computer Networks · Routing: Distance Vector and Link State Routing · 2 marks · Multiple choice

The network uses distance-vector routing and is initialized with direct-link costs. Wait for convergence after each change. How many links will carry no routed traffic because their direct costs exceed a shorter alternative?

Diagram for GATE 2010 CS (CS1) question 64
  1. 4
  2. 3
  3. 2
  4. 1

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Show answer and explanation

Correct answer: (C) 2

Explanation

The R1–R2 link costs six, while R1→R3→R2 costs 3+2=5. The R4–R6 link costs eight, while R4→R5→R6 costs 1+4=5. Every other link is itself a shortest route between its endpoints. Thus exactly two links are unused after convergence, C.

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