Hello. It seems that ispconfig3 is set to redirect www,mysite,abc to mysite,abc by default. If i create www,mysite,abc website instead of mysite,com i can not get there as browser drops to nonexistent mysite,abc and shows apache2 default page. If i add any kind of redirection from mysite,abc to www,mysite,abc browser issues error saying that there is too much redirection (loop). How to make www,mysite,abc to be default address for my site using ispconfig functionality only?
No, that's not the case, ISPConfig does not set any kind of redirect by default, unless you configure it on the redirect tab after adding the website. The most likely reason is that you set a wrong domain in your cms, e.g. in WordPress. Check the settings of your cms.