Fast flux takes advantage of an option built into the Web's architecture, which allows site owners to switch the Internet Protocol address of a site without changing its domain name.

FORBES: Future Phishing

We tried it then and it couldn't have been easier, logging in while connected to your home network flips the switch based on IP address or MAC address, and then it worked at home or on the go, no password necessary.

ENGADGET: Adobe pushes TV Everywhere forward with Adobe Pass 2.0, promises easier logins on more devices

Facebook has made clear that users can reverse the switch and restore their previously listed email as a default address.

WSJ: Facebook's Email Change Riles Users

MCI's orders to switch customers to itself by claiming the orders were sent to the wrong address.

ECONOMIST: Two wobbly titans