I am running WP multisite 4.0.1 on a Windows 2003 IIS 6 dedicated server, so I can do everything I need on it.
I have installed the Domain Mapping plugin and I have been able to have it up and running (no alert on the dashboard of the plugin).
My WP main site is hosted on a domain http://www.mycompany.com.
I sell a product and for each of my customers, the product is hosted on mycustomerX.myproduct.com.
I want to provide a blog for each of my customer hosted on http://www.mycustomerX.myproduct.com.
To test this, I have defined a A record on subdomain http://www.mycustomer1.myproduct.com which redirects to the IP adress of the server.
When I go to the blog I want to access using this subdomain and try to assign the subdomain using the plugin panel, I get the following error: Domain name is unavailable to access.
So just for test purposes, I tested on another domain pointing on the same server and I am sure it is available, and get the same error.
So something is wrong in my settings.
Thanks in advance for tour feedback.