Subnet masks for a Class C network (small network ... 001 to 110 (000 and 111 are reserved), and each subnet can have 30 hosts from 00001 to 11110. Likewise, 00000 and 11111 are reserved: 00000 ...

Perhaps the most recognizable aspect of subnetting is the subnet mask. Like IP addresses, a subnet mask contains four bytes (32 bits) and is often written using the same dotted-decimal notation.