GATE 2012 CS (CS1) – Question 33

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

In classful IPv4, how many Class C networks are possible?

$2^{14}$
$2^7$
$2^{21}$
$2^{24}$

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Correct answer: (C) $2^{21}$

Explanation

Class C begins with fixed prefix bits 110. The first three octets identify the network, leaving 24−3=21 variable network-number bits. Therefore 2²¹ Class C network identifiers exist, option C. Each has an eight-bit host field.

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