I have a Macbook Pro Mid 2012 with Mountain Lion. The goal is to have an ip address that never changes, even after reboot or changing to a different wireless network.
I followed the steps from this link - http://www.macinstruct.com/node/550 and it works for 'ethernet' connections. It tells you to go to network advanced settings and to use "Using DHCP with Manual Address" under the TCP/IP tab.
It does not work for 'Wi-Fi' connections. Does anybody know how to make it work for 'Wi-Fi'?