Set up correct NS Server

[beli3ver]

Hello,

I install Vesta CP with this hostname server.example.de.
Now I want to use my Server as main NS Server.
I have a second server with the servername server2.example.de

So my question is, after the installation I have in the CP the domain server.example.de.
Should I now create exmaple.de and make a A record for server2.example.de? Or create server2.example.de as own Domain?
Or could I removed servere.example.de Domain from Vesta and create example.de and then set the recorders for server and server2...

What is here the best way?

Thanks