mDNSResponder

Bonjour, also known as zero-configuration networking, enables automatic
discovery of devices and services on a local network using industry standard IP
protocols. Bonjour makes it easy to discover, publish, and resolve network
services with a sophisticated, yet easy-to-use, programming interface that is
accessible from Cocoa, Ruby, Python, and other languages.

The mDNSResponder project is a component of Bonjour, Apple's ease-of-use IP
networking initiative.

WWW: https://developer.apple.com/bonjour/
WWW: http://opensource.apple.com/tarballs/mDNSResponder/