Active Directory Forest and Domain Levels

 

Features that are available at domain functional levels

The following table shows the features that are available at each domain functional level.

Domain functional level	Available features	Supported domain controller operating systems
Windows 2000 native	All of the default AD DS features and the following directory features are available: Universal groups for both distribution and security groups. Group nesting Group conversion, which allows conversion between security and distribution groups Security identifier (SID) history. Note In Windows Server 2008 R2, the Personal Virtual Desktop feature was introduced. It requires the Windows 2000 native domain functional level	Windows Server 2008 R2 Windows Server 2008 Windows Server 2003 Windows 2000
Windows Server 2003	All the default AD DS features, all the features that are available at the Windows 2000 native domain functional level, and the following features are available: The domain management tool, Netdom.exe, which makes it possible for you to rename domain controllers Logon time stamp updates The lastLogonTimestamp attribute is updated with the last logon time of the user or computer. This attribute is replicated within the domain. The ability to set the userPassword attribute as the effective password on inetOrgPerson and user objects The ability to redirect Users and Computers containers. By default, two well-known containers are provided for housing computer and user accounts, namely, cn=Computers,<domain root> and cn=Users,<domain root>. This feature allows the definition of a new, well-known location for these accounts. The ability for Authorisation Manager to store its authorisation policies in AD DS Constrained delegation Constrained delegation makes it possible for applications to take advantage of the secure delegation of user credentials by means of Kerberos-based authentication. You can restrict delegation to specific destination services only. Selective authentication Selective authentication makes it is possible for you to specify the users and groups from a trusted forest who are allowed to authenticate to resource servers in a trusting forest.	Windows Server 2012 R2 Windows Server 2012 Windows Server 2008 R2 Windows Server 2008 Windows Server 2003
Windows Server 2008	All of the default AD DS features, all of the features from the Windows Server 2003 domain functional level, and the following features are available: Distributed File System (DFS) replication support for the Windows Server 2003 System Volume (SYSVOL) Last Interactive Logon Information Fine-grained password policies Personal Virtual Desktops	Windows Server 2012 R2 Windows Server 2012 Windows Server 2008 R2 Windows Server 2008
Windows Server 2008 R2	All default Active Directory features, all features from the Windows Server 2008 domain functional level, plus the following features: Authentication mechanism assurance, which packages information about the type of logon method (smart card or user name/password) that is used to authenticate domain users inside each user’s Kerberos token. When this feature is enabled in a network environment that has deployed a federated identity management infrastructure, such as Active Directory Federation Services (AD FS), the information in the token can then be extracted whenever a user attempts to access any claims-aware application that has been developed to determine authorisation based on a user’s logon method. Automatic SPN management for services running on a particular computer under the context of a Managed Service Account when the name or DNS host name of the machine account changes.	Windows Server 2012 R2 Windows Server 2012 Windows Server 2008 R2
Windows Server 2012	The KDC support for claims, compound authentication, and Kerberos armoring KDC administrative template policy has two settings (Always provide claims and Fail unarmored authentication requests) that require Windows Server 2012 domain functional level.	Windows Server 2012 R2 Windows Server 2012
Windows Server 2012 R2	DC-side protections for Protected Users. Protected Users authenticating to a Windows Server 2012 R2 domain can no longer: Authenticate with NTLM authentication Use DES or RC4 cipher suites in Kerberos pre-authentication Be delegated with unconstrained or constrained delegation Renew user tickets (TGTs) beyond the initial 4 hour lifetime Authentication Policies (forest-based Active Directory) Authentication Policy Silos	Windows Server 2012 R2

 

Features that are available at forest functional levels

The following table shows the features that are available at each forest functional level.

Forest functional level	Available features	Supported domain controllers
Windows 2000	All of the default AD DS features are available.	Windows Server 2008 R2 Windows Server 2008 Windows Server 2003 Windows 2000
Windows Server 2003	All of the default AD DS features, and the following features, are available: Forest trust Domain rename Linked-value replication (change group membership replicate values for individual members instead of replicating the entire membership ) The ability to deploy a read-only domain controller (RODC) Improved Knowledge Consistency Checker (KCC) algorithms and scalability The ability to create instances of the dynamic auxiliary class named dynamicObject in a domain directory partition The ability to convert an inetOrgPerson object instance into a User object instance, and to complete the conversion in the opposite direction The ability to create instances of new group types to support role-based authorisation. These types are called application basic groups and LDAP query groups. Deactivation and redefinition of attributes and classes in the schema. The following attributes can be reused: ldapDisplayName, schemaIdGuid, OID, and mapiID. Domain-based DFS namespaces running in Windows Server 2008 Mode, which includes support for access-based enumeration and increased scalability.	Windows Server 2012 R2 Windows Server 2012 Windows Server 2008 R2 Windows Server 2008 Windows Server 2003
Windows Server 2008	All of the features that are available at the Windows Server 2003 forest functional level, but no additional features are available. All domains that are subsequently added to the forest, however, operate at the Windows Server 2008 domain functional level by default.	Windows Server 2012 R2 Windows Server 2012 Windows Server 2008 R2 Windows Server 2008
Windows Server 2008 R2	All of the features that are available at the Windows Server 2003 forest functional level, plus the following features: Active Directory Recycle Bin, which provides the ability to restore deleted objects in their entirety while AD DS is running. All domains that are subsequently added to the forest will operate at the Windows Server 2008 R2 domain functional level by default. If you plan to include only domain controllers that run Windows Server 2008 R2 in the entire forest, you might choose this forest functional level for administrative convenience. If you do, you will never have to raise the domain functional level for each domain that you create in the forest.	Windows Server 2012 R2 Windows Server 2012 Windows Server 2008 R2
Windows Server 2012	All of the features that are available at the Windows Server 2008 R2 forest functional level, but no additional features. All domains that are subsequently added to the forest will operate at the Windows Server 2012 domain functional level by default.	Windows Server 2012 R2 Windows Server 2012
Windows Server 2012 R2	All of the features that are available at the Windows Server 2012 forest functional level, but no additional features. All domains that are subsequently added to the forest will operate at the Windows Server 2012 R2 domain functional level by default.	Windows Server 2012 R2

 

Guidelines for raising domain and forest functional levels

The following guidelines apply to raising the domain or forest functional levels:

You must be a member of the Domain Admins group to raise the domain functional level.

You must be a member of the Enterprise Admins group to raise the forest functional level.

You can raise the domain functional level on the primary domain controller (PDC) emulator operations master only. The AD DS administrative tools that you use to raise the domain functional level (the Active Directory Domains and Trusts snap-in and the Active Directory Users and Computers snap-in) automatically target the PDC emulator when you raise the domain functional level.

You can raise the forest functional level on the schema operations master only. Active Directory Domains and Trusts automatically targets the schema operations master when you raise the forest functional level.

You can raise the functional level of a domain only if all domain controllers in the domain run the version or versions of Windows Server that the new functional level supports.

You can raise the functional level of a forest only if all domain controllers in the forest run the version or versions of Windows Server that the new functional level supports.

You cannot set the domain functional level to a value that is lower than the forest functional level, but you can set it to a value that is equal to or higher than the forest functional level.

With versions of Windows Server that are earlier than Windows Server 2008 R2, you cannot roll back or lower a functional level under any circumstances. If you have to revert to a lower functional level with a version of Windows Server that is earlier than Windows Server 2008 R2, you must rebuild the domain or forest or restore it from a backup copy.

After you set the domain functional level, you cannot roll back or lower the domain functional level except in the cases listed in the following table. The domain functional level can be lowered only by using Windows PowerShell.

Current domain functional level	Current forest functional level	Rollback options
Windows Server 2012 R2	Windows Server 2012 R2	None unless you first lower forest functional level
Windows Server 2012 R2	Windows Server 2012	Windows Server 2012
Windows Server 2012 R2	Windows Server 2008 R2	Windows Server 2012 or Windows Server 2008 R2
Windows Server 2012 R2	Windows Server 2008	Windows Server 2012, Windows Server 2008 R2, or Windows Server 2008
Windows Server 2012	Windows Server 2012	None unless you first lower forest functional level
Windows Server 2012	Windows Server 2008 R2	Windows Server 2008 R2
Windows Server 2012	Windows Server 2008	Windows Server 2008 R2 or Windows Server 2008
Windows Server 2008 R2	Windows Server 2008 R2	None unless you first lower forest functional level
Windows Server 2008 R2	Windows Server 2008	Windows Server 2008
Windows Server 2008 or lower	Windows Server 2008 or lower	None

After you set the forest functional level, you cannot roll back or lower the forest functional level except in the cases listed in the following table. The forest functional level can be lowered only by using Windows PowerShell.

 

Current forest functional level	Recycle Bin enabled?	Rollback options
Windows Server 2012 R2	Yes	Windows Server 2012 or Windows Server 2008 R2
Windows Server 2012 R2	No	Windows Server 2012, Windows Server 2008, or Windows Server 2008 R2
Windows Server 2012	Yes	Windows Server 2008 R2
Windows Server 2012	No	Windows Server 2008 R2 or Windows Server 2008
Windows Server 2008 R2	Yes	None
Windows Server 2008 R2	No	Windows Server 2008

 

Source material: http://technet.microsoft.com/en-us/library/understanding-active-directory-functional-levels(v=ws.10).aspx