I have solved the original problem.
I've edited my HOSTS file to point the Domain Names to the IP I'm using. And it now works for all the domains I setup in ISPConfig.
The flow on effect of all these discussions is that I've also got the HTTPS working now.
Thank you all for your guidance.
I would like to figure out how to make use of my DNS sever. So if you don't mind, I would like to keep this topic going.