All courses › Databases, Networks and Security › Subnetting

Subnetting

A network is split into smaller subnets by using more bits for the network part. The number of addresses in a subnet is two to the power of the number of host bits. Two addresses are lost: the network address and the broadcast address.

N = 2^{32 - p}

addresses in a /p network

H = 2^{32 - p} - 2

usable host addresses

Symbols

$p$	prefix length
$H$	number of machines that fit

Example

A /26 network:

$2^{6} - 2 = 62$ usable addresses.

One step longer prefix halves the number of addresses.

Practise iP networks and subnetting for free →

← IP addresses · Transfer time →

Part of Databases, Networks and Security: IP networks and subnetting.