Prepare Current Forest (Universal Group Location)
You must indicate where you need to create the universal groups in the forest. The Universal Group Location page uses the domain in which the computer that you are logged on to is a member of as the default. If you would prefer to create the universal groups in a domain other than the default Local domain, select Domain FQDN and type the fully qualified domain name (FQDN) in the text box. Providing an alternate domain is helpful when you are running the forest preparation task from a domain other than where you want the universal groups be created. Click Next to continue.