For example, if the publicly registered domain name is Contoso.com, a sub-domain of Corp.contoso.com can be used. [3/3] Make the name the same as a publicly registered domain name. [...] Most Small Business Server customers should use the first method. ↑ "Information about configuring Active Directory domains by using single-label DNS names". support.microsoft.com. ↑ "Internal Domain Information (OEM)".