The classic /24 LAN. The most common subnet size you will ever see. 254 usable hosts on a single LAN.
The most common subnet size you will ever see. 254 usable hosts on a single LAN.
The /24 subnet uses 255.255.255.0 as its subnet mask — meaning the first 24 bits of every address identify the network, and the remaining 8 bits identify the host within that network. That gives you 256 total addresses (254 usable on standard RFC math, after subtracting the network and broadcast addresses).
The wildcard mask — the bitwise inverse of the subnet mask — is 0.0.0.255. Wildcards are what Cisco access-control lists and OSPF area definitions use instead of subnet masks; the "1" bits mark "don't care" positions. For a /24, that leaves 8 don't-care host bits.
To find the network address for any IP in a /24 block, perform a bitwise AND between the IP and the subnet mask. To find the broadcast, OR the network address with the wildcard. Modern tools — like our subnet calculator — do this in microseconds, but the underlying mechanics are straightforward binary arithmetic.
The single most common subnet size in practice. A /24 is the classic LAN: 254 usable hosts (251 on AWS or Azure), 255.255.255.0 mask, easy to read in dotted-decimal. AWS and GCP suggest /24 as a default subnet size.
Cloud-provider quirks matter at every prefix size: AWS and Azure reserve 5 IPs per subnet, GCP reserves 4, and OCI reserves 3. So a /24 on standard RFC math gives you 254 usable hosts, but on AWS or Azure that drops to 251. The capacity-planning gap bites hardest at small prefixes (a /28 has 14 usable on paper, only 11 on AWS) but exists at every size. Our cloud-aware calculator applies the right math automatically.
A /24 subnet has 254 usable hosts on standard RFC math. On AWS or Azure (which reserve 5 IPs per subnet), you get 251 usable. On GCP (4 reserved), 252. On OCI (3 reserved), 253.
The /24 prefix corresponds to subnet mask 255.255.255.0. The matching wildcard mask (used in Cisco ACLs) is 0.0.0.255.
Apply a bitwise AND between the IP and the subnet mask to get the network address. OR the network address with the wildcard mask to get the broadcast. For example, 192.168.1.0/24 has 256 total addresses, with the first being the network address and the last being the broadcast.
A /24 fits an entire LAN's hosts (254 usable) into a single octet boundary, which makes the addressing easy to read and the broadcast domain a manageable size. AWS, Azure, and GCP all recommend /24 as a default starting point for a tier or AZ subnet.