Must Remind (Keep in Mind)
128 | 1 0 0 0 0 0 0 0 (i.e. 1 Bit ON and 7 OFF)
192 | 1 1 0 0 0 0 0 0 (i.e. 2 Bits ON and 6 OFF)
224 | 1 1 1 0 0 0 0 0 (i.e. 3 Bits ON and 5 OFF)
240 | 1 1 1 1 0 0 0 0 (i.e. 4 Bits ON and 4 OFF)
248 | 1 1 1 1 1 0 0 0 (i.e. 5 Bits ON and 3 OFF)
252 | 1 1 1 1 1 1 0 0 (i.e. 6 Bits ON and 2 OFF)
254 | 1 1 1 1 1 1 1 0 (i.e. 7 Bits ON and 1 OFF)
255 | 1 1 1 1 1 1 1 1 (i.e. 8 Bits ON and 0 OFF)
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