For some reason, you might need to find the MAC address of your Apple Airport Extreme. It took me few minutes to find it, so I decided to write a post about this topic.
First, MAC address is a unique identifier of network interfaces. Every gadget that can connect to network (via WiFi, via Bluetooth or via network cable) has MAC address. Some routers and other network devices rely on MAC address to uniquely differentiate other devices.
From a Mac computer (not to be confused with MAC address), open Airport Utility app (located in Utilities folder). It will detect our Airport Extreme in the network, probably more than one. Click on the device you want to observe and it will show a pop-up display with the device name. Hover your mouse on the device name and it will show another pop-up display with the device model and three MAC addresses (for ethernet, 2.4GHz Wi-Fi and 5GHz Wi-Fi).
You can also do this from iPhone / iPad by downloading the official Airport Utility app from AppStore. Open the app, tap on the device’s icon, then choose Hardware Info. Similar information will be displayed.
Supposedly the same guide also applies for Apple Airport Express. However I haven’t tried that myself since I don’t have Airport Express. Please do let me know if it works for you.