I think it becomes a relative path without the final/root dot. That is, "example.net" in the zone file "mydomain.com" will be understood as "example.net.mydomain.com.".

Yes, unless you mean something different, here are articles about it: http://www.dns-sd.org/TrailingDotsInDomainNames.html

http://web.archive.org/web/20080326233315/http://homepages.t...

You don't if you're running tinydns: http://cr.yp.to/djbdns/tinydns-data.html