Telecom & Networking

Intermediate

Usable Subnet Hosts

Number of usable IPv4 addresses in a subnet with an n-bit prefix.

Formula

H = 2^{(32-n)} - 2

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Variables

HUsable hosts

nPrefix length (bits)

Example

/24 network: H = 2⁸ - 2 = 254

Did You Know?

Two addresses are always reserved: one for the network itself and one for broadcast.

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