The GATE Grind

GATE 2025 CS (CS2) – Question 23

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

Consider a network that uses Ethernet and IPv4. Assume that IPv4 headers do not use any options field. Each Ethernet frame can carry a maximum of 1500 bytes in its data field. A UDP segment is transmitted. The payload (data) in the UDP segment is 7488 bytes.

Which ONE of the following choices has the CORRECT total number of fragments transmitted and the size of the last fragment including IPv4 header?

  1. 5 fragments, 1488 bytes
  2. 6 fragments, 88 bytes
  3. 6 fragments, 108 bytes
  4. 6 fragments, 116 bytes

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Correct answer: (D) 6 fragments, 116 bytes

Explanation

The IP payload is 7488 + 8 (UDP header) = 7496 bytes, and each fragment carries at most 1480 data bytes. 5 full fragments carry 7400 bytes, leaving 96 bytes for a 6th fragment. Its size with the 20-byte header is 116 bytes.