[2] It allows a device providing services, such as file sharing, printer sharing, or remote log-in, to sleep, i.e. enter a low-power mode, while its services remain available, even world-wide, by registering with a sleep proxy server on the local network.
[4] The service uses the Wake on Demand feature, first offered in Mac OS X Snow Leopard.
When a packet arrives, from anywhere on the Internet, for a proxied service, the sleep proxy server wakes the sleeping host and reverses the above process, using ARP and NDP again to re-associate the same IP addresses with the proper machine, and any service proceeds as if the server had not slept.
Early implementations of Wake on LAN (WoL) required wired network interfaces.
Some examples of supported services are:[4] Implementations on a local area network can be seen with Bonjour Browser.