Quoting Didier Kryn (kryn@???):

>     Avahi daemon is the Linux dnssd service. dnssd is a protocol
> for service discovery on LAN (formerly known as Apple "Bonjour").
> The essential utility for me is to allow to discover CUPS servers on
> the LAN, because recent versions of CUPS advertise their presence by
> the dnssd protocol instead of the former ad hoc protocol.

dnssd is the most annoyingly and pointlessly chatty network protocol
since Appletalk. If like me you don't want that crud junking up your
network, edit the line 'BrowseRemoteProtocols dnssd cups' in cupsd.conf
to 'BrowseRemoteProtocols none' and restart cupsd. Blessed silence will
ensue.

This of course requires determining a target printer's IP address and
supported network transports, when configuring printing, rather than
having it be automagical. (Quelle horreur!)

(Check the authors of Avahi, and you'll see a familiar name.)