في شبكة فئوية (classful network) التصميم IPv4 اعطى عنوان للشبكه في حجم 8 او 16 او 24 بت فقط ويعطي فئه اما A او B او C .
Classful network design for IPv4 sized the network address as one or more 8-bit groups, resulting in the blocks of Class A, B, or C addresses.