IPv4 Network Subnet Prefixes, Masks, Usable Hosts

The following table shows the IPv4 network subnet prefixes, subnet masks, and the number of usable hosts.

Prefix size Network mask Available subnets Usable hosts per subnet Total usable hosts
/24 255.255.255.0 1 254 254
/25 255.255.255.128 2 126 252
/26 255.255.255.192 4 62 248
/27 255.255.255.224 8 30 240
/28 255.255.255.240 16 14 224
/29 255.255.255.248 32 6 192
/30 255.255.255.252 64 2 128
/31 255.255.255.254 128 2 * 256

* for point-to-point links only

In a subnet the following two addresses cannot be assigned to hosts:

  • the first address is the address of the subnet,
  • the last address is the broadcast address to all hosts.

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