As noted earlier in this chapter, Active Directory in Windows Server 2008 R2 hasn’t changed to the point where organizations with solid Active Directory structures have to make changes to their directory environment. Forests, domains, sites, organizational units, groups, and users all remain the same. There are several improvements made in Active Directory and the breadth of functionality provided by directory services in Windows Server 2008 R2.
The changes made in Active Directory are captured in the name changes of directory services as well as the introduction of a Read-Only Domain Controller service introduced in Windows Server 2008.
Renaming Active Directory to Active Directory Domain Services
In Windows Server 2008, Active Directory was renamed to Active Directory Domain Services (AD DS), and Windows Server 2008 R2 continues with that new name. Active Directory Domain Services refers to what used to be just called Active Directory with the same tools, architectural design, and structure that Microsoft introduced with Windows 2000 and Windows 2003.
The designation of Domain Services identifies this directory as the service that provides authentication and policy management internal to an organization where an organization’s internal domain controls network services. For the first time, AD DS can be stopped and started as any other true service. This facilitates AD DS maintenance without having to restart the domain controller in Directory Services Restore Mode.
Renaming Active Directory in Application Mode to Active Directory Lightweight Directory Service
Another name change in the directory services components with Windows Server 2008 from Microsoft is the renaming of Active Directory in Application (ADAM) to Active Directory Lightweight Directory Services (AD LDS). ADAM has been a downloadable addin to Windows 2003 Active Directory that provides a directory typically used in organizations for nonemployees who need access to network services. Rather than putting nonemployees into the Active Directory, these individuals—such as contractors, temporary workers, or even external contacts, such as outside legal counsel, marketing firms, and so on—have been put in ADAM and given rights to access network resources such as SharePoint file libraries, extranet content, or web services.
AD LDS is identical to ADAM in its functionality, and provides an organization with options for enabling or sharing resources with individuals outside of the organizational structure. With the name change, organizations that didn’t quite know what ADAM was before have begun to leverage the Lightweight Directory Services function of Active Directory for more than resource sharing but also for a lookup directory resource for clients, patients, membership directories, and so on.
Expansion of the Active Directory Federation Services
That leads to the third Active Directory service called Active Directory Federation Services, or AD FS. Active Directory Federation Services was introduced with Windows 2003 R2 edition and continues to provide the linking, or federation, between multiple Active Directory forests, or now with Windows Server 2008 R2 Active Directory Federation Services, the ability to federate between multiple Active Directory Domain Services systems.
Effectively, for organizations that want to share information between Active Directory
Domain Services environments, two or more AD DS systems can be connected together to share information. This has been used by organizations that have multiple subsidiaries with their own Active Directory implemented to exchange directory information between the two organizations. And AD FS has been used by business trading partners (suppliers and distributors) to interlink directories together to be able to have groups of users in both organizations easily share information, freely communicate, and easily collaborate between the two organizations.
Introducing the Read-Only Domain Controller
Another change in Active Directory in Windows Server 2008 that was continued in Windows 2008 R2 was the addition of a Read-Only Domain Controller, or RODC. The RODC is just like a global catalog server in Active Directory used to authenticate users and as a resource to look up objects in the directory; however, instead of being a read/write copy of the directory, an RODC only maintains a read-only copy of Active Directory and forwards all write and authentication requests to a read/write domain controller.
RODCs can also be configured to cache specified logon credentials. Cached credentials speed up authentication requests for the specified users. The cached credentials are stored in cache on the RODC system, not every object in the entire global catalog. If the RODC is shut down or powered off, the cache on the RODC is flushed, and the objects in cache are no longer available until the RODC connects back to a global catalog server on the network.
The RODC is a huge advancement in the area of security being that a RODC cannot be compromised in the same manner that a global catalog server can be in the event of a physical theft of a domain server. Organizations that require the functionality of a global catalog server for user authentication that have the global catalog server in an area that is not completely secure, such as in a remote office, in a branch office location, or even in a retail store outlet, can instead put a RODC in the remote location.
Source of Information : Sams - Windows Server 2008 R2 Unleashed