I see that avahi-dnsconfd achieve to handle dns request from the browser without being listed in /etc/resolv.conf. I think that it's part of the dns resolution spec to check whether or not localhost can answer the query first.
The problem is that, it looks like, there's nobody on port 53. So how does avahi catch dns lookups and answer it ?
avahi is using nsswitch.conf to handle dns configuration.