The first four bits of 192.168.1.0: This places the network in the Class C range and also fixes the length of the network address at 24 bits. To subnet this network, more than 24 bits must be set ...

Subnet masks for a Class C network (small network) use the first 24 bits for subnet ID and the last 8 for host ID. These last 8 are divided between hosts and subnets (for more on network classes ...