Apple AirPort Extreme 802.11n (2nd Generation) - Manual (Page 9)

Chapter 1 Getting Started 9
After you have connected the cables for all the devices you plan to use, connect the AC
plug adapter to the power port, and plug AirPort Extreme into the wall. There is no “on”
switch.
Important: Use only the AC adapter that came with your AirPort Extreme.
When you plug the AirPort Extreme AC adapter into the wall, the status light flashes
green for one second, and then glows amber while it starts up. After it has started up
completely, the status light flashes amber. The status light glows solid green after
AirPort Extreme is properly set up and connected to the Internet or a network.
When you connect Ethernet cables to the Ethernet ports, the lights above them glow
solid.
Power port Ethernet activity light
AC adapter