urpmi can automatically find the media repository path using DNS-SD
(Zeroconf), with the "--zeroconf" option:
  urpmi.addmedia --distrib --zeroconf
  urpmi.addmedia --zeroconf main media/main/release

This option can also be used together with the "--mirrorlist" option,
in which case the repositories are configured using Zeroconf if found,
and mirrorlist is used as a fallback:
  urpmi.addmedia --distrib --zeroconf --mirrorlist

When searching for the repository using Zeroconf, the request timeouts
after a delay of 10 seconds, to avoid hanging urpmi if some hosts are
unresolvable.

If a repository is found using DNS-SD, urpmi.addmedia will build a
complete repository path using fields from /etc/product.id, this way:
<advertised repository path>/lowercase(<branch>)/<version>/<arch>

To advertise an urpmi repository using DNS-SD, a service record with
the instance "_mdv_urpmi" has to be created, specifying the target
host and target port where the service is located.
In addition, two DNS-SD TXT records must be specified, in the form of
key/value pairs: protocol (http, ftp or rsync) and path (repository root).

The path value should be the full path to the media repository root,
for example /dis if the distribution repository is reachable on
http://host:port/dis/official/2010.1/i586

See the urpmi-repository-http.service file for an example of urpmi
repository advertising using Avahi.