What is a /24 subnet?

A /24 fixes the first 24 bits of the address as the network and leaves 8 for hosts — 256 addresses in all.

Of those, 254 can be given to a machine: the first address names the network itself, and the last is the broadcast address.

These are the everyday sizes. A /24 is one office, one VLAN or one cloud subnet; the smaller ones suit a rack, a service tier or a DMZ.

A /24 is the size most people picture when they think of a subnet: one whole final octet.