It is important to understand that AD DS is a product in constant development since its release with Windows 2000. From humble beginnings, Active Directory as a product has developed and improved over the years. The first major set of improvements to AD was released with the Windows Server 2003 product. Many of the improvements made with Windows Server 2003 AD still exist today in Windows Server 2008 R2 AD DS. It is subse quently important to understand what functionality in AD was born from Windows Server 2003. The following key improvements were made in this time frame:
. Windows Server 2003 Active Directory Domain Rename Tool—Windows Server 2003 originally introduced the concept of Domain Rename, which has continued to be supported in Windows Server 2008 R2. This gives administrators the ability to prune, splice, and rename AD DS domains. Given the nature of corporations, with restructuring, acquisitions, and name changes occurring constantly, the ability of AD DS to be flexible in naming and structure is of utmost importance. The Active Directory Domain Rename Tool was devised to address this very need. Before AD DS domains can be renamed, several key prerequisites must be in place before the domain structure can be modified. First, and probably the most important, all domain controllers in the entire forest must be upgraded to Windows Server 2003 or 2008 in advance. In addition, the domains and the forest must be upgraded to at least Windows Server 2003 functional level. Finally, comprehensive backups of the environment should be performed before undertaking the rename. The domain rename process is complex and should never be considered as routine. After the process, each domain controller must be rebooted and each member
computer across the entire forest must also be rebooted (twice).
. Cross-forest transitive trust capabilities—Windows Server 2003 Active Directory introduced the capability to establish cross-forest transitive trusts between two disparate AD DS forests. This capability allows two companies to share resources more easily, without actually merging the forests. Note that both forests must be running at least at Windows Server 2003 functional levels for the transitive portion of this trust to function properly.
. AD DS replication compression disable support—Another feature introduced in Windows Server 2003 AD was the ability to turn off replication compression to increase domain controller performance. This would normally be an option only for organizations with very fast connections between all their domain controllers.
. Schema attribute deactivation—Developers who write applications for AD DS continue to have the ability, introduced in Windows Server 2003, to deactivate schema attributes, allowing custom-built applications to utilize custom attributes without fear of conflict. In addition, attributes can be deactivated to reduce replication traffic.
. Incremental universal group membership replication—Before Windows Server 2003, Windows 2000 Active Directory had a major drawback in the use of universal groups. Membership in those groups was stored in a single, multivalued attribute in AD DS. Essentially, what this meant was that any changes to membership in a universal group required a complete re-replication of all membership. In other words, if you had a universal group with 5,000 users, adding number 5,001 would require a major replication effort because all 5,001 users would be re-replicated across the forest. Windows Server 2003 and 2008 simplify this process and allow for incremental replication of universal group membership. In essence, only the 5,001st member is replicated in Windows Server 2003/2008.
. AD–integrated DNS zones in application partitions—Windows Server 2003 improved DNS replication by storing DNS zones in the application partition. This basically meant that fewer objects needed to be stored in AD, reducing replication concerns with DNS.
. AD lingering objects removal—Another major improvement originally introduced with Windows Server 2003 and still supported in 2008 is the ability to remove lingering objects from the directory that no longer exist.
Source of Information : Sams - Windows Server 2008 R2 Unleashed