http://www.dns-sd.org/ DNS-SD is a protocol for enabling the automatic discovery and configuration of network services such as printers, websites, music collections, file shares, etc. As the name suggests, it utilises standard DNS messages and servers.
DNS-SD has been implemented and marketed under a number of different names, including Rendezvous, Bonjour, and Avahi. It is used in Zeroconf networks.
