bit  hex  deci  num
===================
/24  .00  .0    256
/25  .80  .128  128
/26  .c0  .192   64
/27  .e0  .224   32
/28  .f0  .240   16
/29  .f8  .248    8
/30  .fc  .252    4
/31  .fe  .254    2
/32  .ff  .255    1