The GATE Grind

GATE 2024 CS (CS2) – Question 32

Computer Networks · IPv4: Addressing, CIDR, Fragmentation and NAT · 1 mark · Multiple select

Which of the following fields of an IP header is/are always modified by any router before it forwards the IP packet?

  1. Source IP Address
  2. Protocol
  3. Time to Live (TTL)
  4. Header Checksum

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Show answer and explanation

Correct answer: (C) Time to Live (TTL); (D) Header Checksum

Explanation

Every router decrements TTL, which forces a header checksum recomputation. Source address and protocol are normally unchanged.