Apple AirPort Extreme 802.11n (4th Generation) - Manual (Page 14)

14 Chapter 2 AirPort Extreme Networks
Using the AirPort Extreme with a Broadband Internet Service
When you set up your AirPort Extreme to provide network and Internet access,
Macintosh computers with AirPort and AirPort Extreme Cards, and 802.11a, 802.11b,
802.11g, and IEEE 802.11n draft specification wireless-equipped computers, can access
the wireless AirPort network to share files, play games, and use Internet applications
like web browsers and email applications.
It looks like this:
DSL or cable modem Internet WAN port
to Internet
<
2.4 GHz
2.4 or 5 GHz