Subnet Addressing Continued
Class A addresses come from the InterNIC with the first octet masked. Class B addresses have the first two octets masked; Class C addresses have the first three octets masked.
TCP/IP devices use the combination of the IP address and the subnet mask to determine if other addresses are local or remote.
The binary AND operation is used to perform the calculation.
The binary AND operation is very simple--one and one results in one, all other combinations result in zero.