Subnetting a network allows more 32-bit IP addresses to be used on a network, given that there are a limited number. IPv4 networks are divided into three classes, each dependent on the size of the network. Class C networks are reserved for IP addresses with the first number between 192 and 223. Each decimal number of the IP address can also be expressed as 8-bit strings of zeroes and ones.
When subnetting a class C network, start out with the default subnet mask, which is used to help create new network IDs. The default subnet mask for class C is 255.255.255.0, with the decimal numbers. Up to 253 hosts can fit on this network; one address is the network ID, one is the broadcast ID, and one is the default gateway to the network's router.
Determine how many subnets are needed for the network. As an example, assume that four subnets are needed. The first two bits of the octet would be designated as the subnet mask, because there are four possible combinations: 00, 01, 10 and 11. Assume that the network IP address is 192.168.0.0, and is also the first subnet ID. The others are 192.168.0.64, 192.168.0.128, and 192.168.0.192. The maximum IP in each is the broadcast ID, leaving the rest of the address available as hosts.