Subnet Address
After the masked portion of the subnet mask, the network identifier changes to zero(s). For example, the network identifier of a host that has IP address 192.168.23.45 with subnet mask 255.255.255.0 is 192.168.23.0.
A TCP/IP host must have a non-zero host identifier. So, for example, on a subnet using mask 255.255.255.0, the IP address 222.12.150.4 is a valid host IP address. However, the address 222.12.150.0 is not a host address, but a network identifier.
Do not expect all subnetwork identifiers to end in a decimal zero. It is true that subnetworks are identified by all the binary digits in the host portion being zero, but that does not mean that the entire last octet will be zero.