Classfull IPv4

Table 12-2 IPv4 Address Classes Based on First Octet Values

Class      First Octet Values      Purpose

A            1–126                         Unicast (large networks)

B            128–191                     Unicast (medium-sized networks)

C            192–223                     Unicast (small networks)

D            224–239                     Multicast

E            240–255                     Reserved (formerly experimental)

address ranges of all addresses that begin with 0 and all addresses that begin with 127 are reserved