Article ID: 2002634 - View products that this article applies to.
Dialog 1: Soft block in Windows Server 2008 DCPROMO warning against the creation of new domains with single-label DNS names:
Dialog 2: Soft block in Windows Server 2008 DCPROMO warning against the creation of replica domain controllers in existing domains with single-label DNS names.
Dialog 3: "Additional Domain Controller Options" illustrating that the option to install the DNS server role is disabled when promoting replica domain controllers into domains with single-label DNS names.
Dialog 4: Windows Server 2008 R2: Hard block in Windows Server 2008 R2 preventing the creation of new Active Directory domains with single-label DNS names.
Title: Active Directory Domain Services Installation Wizard
To prevent Windows Server 2008 and Windows Sever 2008 R2 domain controllers from creating new domains with single-label DNS names that might result in application compatibility issues:
Some Microsoft products may continue to function with single-label domains and other namespace configurations, however, they are not a recommended configuration for future deployments. Microsoft recommends that customers deploy infrastructure using common, tested configurations to minimize extra deployment and testing costs.
Microsoft will continue to provide customers with existing single-label domain configurations with best-effort support, such that Microsoft remains committed to triaging and evaluating any technical issues that customers experience. For more information, see the following article in the Microsoft Knowledge Base:
The best practice is to create Active Directory forest root domains with fully qualified DNS names that consist of two or more name parts separated by a period (i.e. contoso.com, corp.contoso.com or contoso.<two letter country code top-level domain> vs. the single-label name contoso. )
This soft block in Windows Server 2008 and hard block in Windows Server 2008 R2 does not affect the promotion of additional Windows Server 2008 or Windows Server 2008 R2 replica domain controllers into existing Active Directory domains with single-label DNS names, which remains fully supported. Similarly, the in-place upgrade of existing domain controllers to the Windows Server 2008 or Windows Server 2008 R2 operating system versions remains fully supported, subject to the upgrade matrix allowed by target operating system.
For more information about Active Directory and single-label DNS names, see the following article in the Microsoft Knowledge Base: