/8 /255.0.0.0
/12 /255.240.0.0
/16 /255.255.0.0
/17 /255.255.128.0
/18 /255.255.192.0
/19 /255.255.224.0
/20 /255.255.240.0
/21 /255.255.248.0
/22 /255.255.252.0
/23 /255.255.254.0
/24 /255.255.255.0
/25 /255.255.255.128
/26 /255.255.255.192
/27 /255.255.255.224
/28 /255.255.255.240
/29 /255.255.255.248
/30 /255.255.255.252
