New Features in Windows Server 2003
Only a few of the new Windows Server 2003 features have a direct impact on Active Directory architecture. Those that do, however, give a lot more flexibility to your designs than was available in Windows 2000. Here are those features:
Domains now can be renamed and their parent/child relationships changed. This helps restructure a forest following a reorganization within a company. Domains cannot be dynamically split off to form their own forests, however, nor can domains from one forest be merged as a unit into another forest. Domain controllers can be renamed as well.
A new trust type called Forest trust supports transitive trust relationships between domains in separate forests. Microsoft calls this a federation. The ability to form a federation greatly simplifies Active Directory operations in an organization such as a conglomerate or a university where entities are constantly being added and removed.
Support was added for digest authentication as described in RFC 2829, "Authentication Methods for LDAP." This makes it easier to integrate Active Directory into non-Windows environments.
Schema components can now be declared "defunct," making it possible to trim away object classes and attributes that were added by an application but are no longer needed.
Support was added for the InetOrgPerson class as defined in RFC 2798, "Definition of the inetOrgPerson LDAP Object Class." This enhances interoperability with Netscape and NetWare directory services, both of which use the inetOrgPerson object class to create user objects.
The maximum number of objects that can be stored in Active Directory was increased to over a billion.