Currently on my SharePoint 2010 install the My Sites section is roped off on a sub-domain (port 80) of the main site collection. Whenever anyone opens the main site it automatically detects their username through AD and logs them in without prompting them. If they try to enter the My Sites sub-domain they are prompted to enter their username and password.
How do I get the My Sites site collection to act like the main site collection in regards to user credentials?