Upgrading Windows Server 2003 domain controllers in Windows Server 2008 R2 and Windows Server 2008 R2 single-label domains is supported.Promoting additional Windows Server 2008 R2 and Windows Server 2008 R2 domain controllers into existing single-label DNS domains is supported.
While Windows Server 2008 R2 additions increase the database size, the addition of a single-instance store that is supported by domain controllers that run Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, or Windows Server 2008 R2 offsets that increase.
Windows Server 2008 R2 domain controllers are estimated to be 10 percent larger than Windows Server 2008 domain controllers, not counting the Active Directory Recycle Bin.
In a production Windows Server 2008 R2 domain at Microsoft, the Active Directory Recycle Bin feature increased the database size by an additional 15 to 20 percent of the original AD DS database size, using the default deleted Object Lifetime and recycled Object Lifetime values of 180 days.
This topic explains the process for upgrading domain controllers to Windows Server 2008 or Windows Server 2008 R2.
This information is based on the experience of the Microsoft Customer Service and Support (CSS) team.
This topic includes links to related information about the upgrade process.To obtain a copy of this guide in a printable file format, see Upgrading Active Directory Domains to Windows Server 2008 and Windows Server 2008 R2 AD DS Domains at the Microsoft Download Center ( For information about each feature, special considerations, and how to prepare for deployment, see Changes in Functionality from Windows Server 2003 with Service Pack 1 (SP1) to Windows Server 2008 ( For information about specific features in Active Directory Domain Services (AD DS) in Windows Server 2008, see Active Directory Domain Services Role ( Some functionality that was available in previous versions of Windows Server is deprecated in Windows Server 2008.For example, SMTP Replication is removed by default.For more information, see article 947057 in the Microsoft Knowledge base ( The Browser Service is disabled by default in Windows Server 2008 and Windows Server 2008 R2 domain controllers.For information about each feature, special considerations, and how to prepare for deployment, see Changes in Functionality from Windows Server 2008 to Windows Server 2008 R2 ( For information about specific features in AD DS in Windows Server 2008 R2, see What's New in Active Directory Domain Services ( In Windows Server 2008 R2, does not allow the creation of a domain that has a single-label Domain Name System (DNS) name.If you try to promote an additional domain controller in a domain that has a single-label DNS name (such as contoso, instead of contoso.com), the check box to install a DNS server is not available in