CLASS A


255.0.0.0 – /8
255.128.0.0 – /9
255.192.0.0 – /10
255.224.0.0 – /11
255.240.0.0 – /12
255.248.0.0 – /13
255.252.0.0 – /14
255.254.0.0 – /15

CLASS B


255.255.0.0 – /16
255.255.128.0 – /17
255.255.192.0 – /18
255.255.224.0 – /19
255.255.240.0 – /20
255.255.248.0 – /21
255.255.252.0 – /22
255.255.254.0 – /23
CLASS C


255.255.255.0 – /24
255.255.255.128 – /25
255.255.255.192 – /26
255.255.255.224 – /27
255.255.255.240 – /28
255.255.255.248 – /29
255.255.255.252 – /30