GATE 2017 CS (CS2) – Question 30

Computer Networks · IPv4: Addressing, CIDR, Fragmentation and NAT · 1 mark · Numerical answer

What is the largest number of IPv4 router addresses that fit in the record-route option of an IPv4 header?

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Correct answer: 9.0 to 9.0

Explanation

An IPv4 header can contain at most 40 option bytes. Record Route uses one byte each for option type, length and pointer, leaving 37 bytes. Each IPv4 router address consumes four bytes, so floor(37/4)=9 addresses fit, with padding for header alignment.

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