In the IPv4 addressing format, the number of networks allowed under Class C addresses is

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Official answer: C) 221

IPv4, CIDR and NAT

In IPv4 classful addressing, a Class C address has the first 3 bits fixed as 110.

The network ID part consists of 24 bits (3 octets).
Since the first 3 bits are fixed, the number of available bits for the network ID is $24 - 3 = 21$ bits.

Therefore, the number of possible Class C networks is $2^{21}$ .

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This IPv4, CIDR and NAT previous year question is Q23 of the GATE CSE 2012 paper. Find more GATE CSE PYQs on IPv4, CIDR and NAT in Computer Networks, or browse all GATE CSE PYQs.

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IPv4, CIDR and NAT in GATE CSE

IPv4, CIDR and NAT has 14 GATE CSE PYQs across 10 papers from 2012 to 2025. 5 of them are 1-mark MCQs like this one, and GATE CSE 2012 has 2.

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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.