It seems that very few people actually know how to find out where a user account is actually located in AD. The easiest way is to start a search on top of your domain, find the user and than the magic trick. Click on top of search box on view and choose columns.
Here you add the "published at".
After you press Ok you will notice that the results will also display where the user is located.
It is also possible to use the distinguished name if you prefer that.