How to repair DNS hostname?

Hello,

I had a working DNS setup with the right Primary address, Current HostName and DNS hostname. While figuring out how to use the Print service my DNS hostname changed. I suspect that when I was adding a printer IP to the DNS list something went wrong. After that the DNS hostname must have changed to the name of the mail server. I discovered that, because I could not access the internet anymore and did a 'changeip -checkhostname' to check the settings. I thought that it was simple to delete the mail-server from the dns list to get the right DNS hostname back. But that's not the case.
After putting in the mail server address the mail did not function either. So my DNS is mess now.
I tried searching in the support discussions for a way to repair this, but could not find an answer that fits the situation.

I am in the middle of a swith over and because everything was working (except the printers) I decided to move all data and mail from the old Windows servers to the new Mac servers. Because the system is in use now for a week I can't simply switch back. So I am stuck in this situation and desperate. Yes, I made a classical mistake not to backup first the working servers. But that happens when you are in a rush to get this done. This is my first Apple server experience and was very happy I came this far with the available Apple docs and discussion support.

Server network situation:
- Mac Mini server1 (en0:10.0.0.1, en2:191.168.0.128 (USB-adaptor)) configured as DHCP, NAT, FireWall and secondary DNS
- Mac Mini server2 (10.0.0.2) configured as Primary DNS, Mail, Open Directory, AFP and SMB

I configured with non-authorative domainname (say mydomain.nl). In the near future I will have a fixed IP-address so the domainname can be used from the internet.

changip -checkhostname on result:
Primary address = 10.0.0.2
Current Hostname = hollandia.mydomain.nl
The DNS hostname is not available, ...

scutil --get LocalHostName = DeHollandia
scutil --get Hostname = hollandia.mydomain.nl
dig -x 10.0.0.2
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id:3354
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;2.0.0.10.in-addr.arpa. IN PTR
;; SERVER: 10.0.0.2#53(10.0.0.2)

DNS configuration:
-mydomain.nl
hollandia Machine 10.0.0.2
beschermer Machine 10.0.0.1
mail Machine 10.0.0.2
-0.0.10.in-addr.arpa.
10.0.0.1 Reverse Mapping beschermer.mydomain.nl
10.0.0.2 Reverse Mapping hollandia.mydomain.nl

Hopes the above info is a start to the solution.