Active Directory

Active Directory (AD) is a directory service that Microsoft developed for Windows domain networks. It is included in most Windows Server operating systems as a set of processes and services. Initially, Active Directory was only in charge of centralized domain management. Starting with Windows Server 2008, however, Active Directory became an umbrella title for a broad range of directory-based identity-related services.

A server running Active Directory Domain Services (AD DS) is called a domain controller. It authenticates and authorizes all users and computers in a Windows domain type network—assigning and enforcing security policies for all computers and installing or updating software. For example, when a user logs into a computer that is part of a Windows domain, Active Directory checks the submitted password and determines whether the user is a system administrator or normal user.

Active Directory uses Lightweight Directory Access Protocol (LDAP) versions 2 and 3, Microsoft's version of Kerberos, and DNS.

Active Directory Federation Services

Active Directory Federation Services (ADFS or AD FS), a software component developed by Microsoft, can run on Windows Server operating systems to provide users with single sign-on access to systems and applications located across organizational boundaries. It uses a claims-based access-control authorization model to maintain application security and to implement federated identity. (Claims-based authentication involves authenticating a user based on a set of claims about that user's identity contained in a trusted token. Such a token is often issued and signed by an entity that is able to authenticate the user by other means, and that is trusted by the entity doing the claims-based authentication.) It is part of the Active Directory Services.

In ADFS, identity federation is established between two organizations by establishing trust between two security realms. A federation server on one side (the Accounts side) authenticates the user through the standard means in Active Directory Domain Services and then issues a token containing a series of claims about the user, including its identity. On the other side, the Resources side, another federation server validates the token and issues another token for the local servers to accept the claimed identity. This allows a system to provide controlled access to its resources or services to a user that belongs to another security realm without requiring the user to authenticate directly to the system and without the two systems sharing a database of user identities or passwords.

Windows Server

Windows Server is a brand name for a group of server operating systems released by Microsoft. It includes all Windows operating systems branded "Windows Server", but not any other Microsoft product. The first Windows server edition to be released under that brand was Windows Server 2003. However, the first server edition of Windows was Windows NT 3.1 Advanced Server, followed by Windows NT 3.5 Server, Windows NT 4.0 Server, and Windows 2000 Server; the latter was the first server edition to include Active Directory, DNS Server, DHCP Server, Group Policy, as well as many other popular features used today.

Members

This brand includes the following operating systems:

Microsoft has also produced Windows Server Essentials (formerly Windows Small Business Server) and Windows Essential Business Server (discontinued), software bundles which includes a Windows Server operating system and some other Microsoft Servers products.

Windows Server 2012

Windows Server 2012, codenamed "Windows Server 8", is the sixth release of Windows Server. It is the server version of Windows 8 and succeeds Windows Server 2008 R2. Two pre-release versions, a developer preview and a beta version, were released during development. The software was generally available to customers starting on September 4, 2012.

Unlike its predecessor, Windows Server 2012 has no support for Itanium-based computers, and has four editions. Various features were added or improved over Windows Server 2008 R2 (with many placing an emphasis on cloud computing), such as an updated version of Hyper-V, an IP address management role, a new version of Windows Task Manager, and ReFS, a new file system. Windows Server 2012 received generally good reviews in spite of having included the same controversial Metro-based user interface seen in Windows 8.

The successor to Windows Server 2012, called Windows Server 2012 R2, was released along with Windows 8.1 in October 2013. A service pack, formally designated Windows Server 2012 R2 Update, was released in April 2014.

Federation

A federation (from Latin: foedus, gen.: foederis, "covenant"), also known as a federal state, is a political entity characterized by a union of partially self-governing states or regions under a central (federal) government. In a federation, the self-governing status of the component states, as well as the division of power between them and the central government, are typically constitutionally entrenched and may not be altered by a unilateral decision of either party, the states or the federal political body.

The governmental or constitutional structure found in a federation is known as federalism. It can be considered the opposite of another system, the unitary state. Germany, with sixteen Bundesländer, is an example of a federation, whereas neighboring Austria and its Bundesländer was a unitary state with administrative divisions that became federated, and neighboring France by contrast has always been unitary.

Federations may be multi-ethnic and cover a large area of territory (e.g. Russia, the United States, or India), although neither is necessarily the case. The initial agreements create a stability that encourages other common interests, reduces differences between the disparate territories, and gives them all even more common ground. At some time this is recognized and a movement is organized to merge more closely. At other times, especially when common cultural factors are at play such as ethnicity and language, some of the steps in this pattern are expedited and compressed.