Thanks a lot for the help. Your setup is very clear.
I’m sure that I entered everything correctly and I still could not resolve any DNS queries from the Zeroshell DNS server.
As a workaround I setup BIND DNS server on my Ubuntu computer and then added the domain as a slave zone on the zeroshell box. It works just fine!
I used EXACTLY the same entries on the Ubuntu BIND which makes me think that we are dealing with a bug or something in Zeroshell.
This will work for now I suppose, although I had really hoped to use the Zeroshell machine as the DNS master server.
Anyways, I very much appreciate the help and excellent examples.