Hi till, thanks for the fast reply as always.
It is excellent to use the default network tool of ubuntu for such a job.
So the default contents of /etc/network/interfaces before installing ispconfig was:
iface lo inet loopback
I think I just go back to that.
I tried it, and only had to reboot computer for the network tool of ubuntu to be re-enabled. Also adding ip addresses there is very easy.
I only wonder what I would have to do if the server was remote ?
Concerning /etc/resolv.conf there was where I always used to edit the dns entries yes. It also takes the dns entries directly from the gui tool of ubuntu. My question was only related to your tutorial's part where you add "dns-nameservers 126.96.36.199 188.8.131.52" inside the /etc/network/interfaces
thanks for the help