Hi Till, when I register a new domain and then I set the dns zone that redirect the user to my web server I get a apache default welcome page. Is it maybe the index.php saved in the /var/www directory? thanks
This might be, depends on your setup. This page is not a pge from ispconfig, it is the default page of your Linux distribution.
If index.php is in the list of index pages in your apache2.conf and php is enabled globally on your server, then this should work.