IP Address Default Subnet Masks

The following table displays the three main IP address classes, along with their default masks in binary and decimal formats, respectively.

Class	Default Mask in Binary	Default Mask in Decimal
A	11111111.00000000.00000000.00000000	255.0.0.0
B	11111111.11111111.00000000.00000000	255.255.0.0
C	11111111.11111111.11111111.00000000	255.255.255.0