Multisite weird issue with redirect

Hey everyone.

I got a weird problem, hoping someone can shed some light into this.

I got a multisite installation of wp. It is set up to host multidomains. I got a couple sites setup everything is fine.

Now the issue is that I added a new site (abc-xyz.com) and I can access its dashboard and its pages BUT if I open the main url abc-xyz.com I get redirected to the main domain/site of the multisite installation. If I append anything to the domain name I get the correct site.

abc-xyz.com falsely redirects to abc.com
abc-xyz.com/? shows the correct site.
abc-xyz.com/index.php shows the correct site.
abc-xyz.com/blog/ shows the correct site.
etc

so basically the “plain” domain is not working in Firefox and Chrome. In IE abc-xyz.com works fine without any extra chars! I checked and there are no redirect rules in htaccess which would explain that behavior.

Does that make any sense?!