See also:
http://tools.ietf.org/html/rfc4632
See also:
http://tools.ietf.org/html/rfc4291#section-2.3 Example: 127.0.0.0/24 will match all IP addresses from 127.0.0.0 to 127.0.0.255
127.0.0.0/31 and 127.0.0.1/31 will both match the IP addresses 127.0.0.0 and 127.0.0.1
127.0.0.254/31 and 127.0.0.255/31 will both match the IP addresses 127.0.0.254 and 127.0.0.255
1:2::3:4 will match the IPv6 address written as 1:2:0:0:0:0:3:4 or 1:2::3:4
::7F00:1 will match the address written as 127.0.0.1, ::127.0.0.1 or ::7F00:1
::1 (IPv6 loopback) will *not* match the address 127.0.0.1