How about following the Domain name conventions and use a Top Level Domain name like everybody else. For example "rrd" the last three characters from your UserId here
That would give you
dashaus.rrd as domain name and
nas.dashaus.rrd and
beastie.dashaus.rrd as host names.
The situation now is that "dashaus" is interpreted like a TLD like "com" or "org", so "beastie.dashaus" and "dashaus-nas.dashaus" are different domains just like "beastie.com" and "dashaus-nas.com" would be totally different domains. Do you see the problem with this setup?