I don't know if it will work the same way on SME, but on microsoft networks, I just add each internal host as a domain in the DNS.
That is, to create an internal mapping for "web.gecka.nc" (and assuming I don't want to affect "xyz.gecka.nc"), I would create a domain named "web.gecka.nc", then set the A record for '@'.
When you create a new domain, SME will automatically create "mail....", "ftp....", and some others -- I think you can delete these from the 'hostnames' panel.
If that doesn't work you will need to create a custom template for 'dnscache' as well as 'tinydns' before internal resolution will work. 'dnscache' needs an entry for each domain in /var/service/dnscache/root/servers indicating where to find authoritative DNS for that "domain". For internally resolved domains, the DNS host to use is "127.0.0.1".
'dnscache' rebuilds all of the .../servers/... files whenever it restarts, so you can't just add a file and restart to test your settings -- you have to modify the templates or /var/service/dnscache/run.