51.255.16.0-51.255.31.255 51.255.16.0/20
51.255.32.0-51.255.63.255 51.255.32.0/19
51.255.64.0-51.255.127.255 51.255.64.0/18
51.255.128.0-51.255.191.255 51.255.128.0/18
51.255.192.0-51.255.223.255 51.255.192.0/19
51.255.224.0-51.255.231.255 51.255.224.0/21