I've installed KDE desktop, that depends on avahi. It has two daemons
Here's the description from debian's avahi-dnsconfd package:
Package: avahi-dnsconfd Description-en: Avahi DNS configuration tool Avahi is a fully LGPL framework for Multicast DNS Service Discovery. It allows programs to publish and discover services and hosts running on a local network with no specific configuration. For example you can plug into a network and instantly find printers to print to, files to look at and people to talk to. . This tool listens on the network for announced DNS servers and passes them to resolvconf so it can use them. This is very useful on autoconfigured IPv6 networks. Homepage: http://avahi.org/
More info should be available at the Avahi home page.