All network administrators are familiar with IPv4, but as IPv6 migrations pick up in different parts of the world, the need for administrators to become familiar with IPv6 becomes important. One familiar address in IPv4 is the loopback address, which is typically used for testing whether your network interface is working by typing ping loopback or ping 127.0.0.1 at a command prompt. The loopback address on an IPv6 network however is 0:0:0:0:0:0:0:1 which is abbreviated as ::1, so if you want to test your network interface in Windows Vista where IPv6 is enabled by default, you can type ping ::1 instead.