Domain:
A domain is a logical
grouping of networked computers in which one or more of the computers has one
or more shared resources, such as a shared folder or a shared printer, and in
which all of the computers share a common central domain directory database
that contains user account security information. One distinct advantage of
using a domain, particularly on a large network, is that administration of user
account security for the entire network can be managed from a centralized
location. In a domain, a user has only one user account, which is stored in the
domain directory database. This user account enables the user to access shared
resources (that the user has permissions to access) located on any computer in
the domain
Active Directory domains can hold
millions of objects, as opposed to the Windows NT domain structure, which was
limited to approximately 40,000 objects. As in previous versions of Active
Directory, the Active Directory database file (ntds.dit) defines the domain.
Each domain has its own ntds.dit file, which is stored on (and replicated
among) all domain controllers by a process called multimaster replication.
The domain controllers manage the configuration of domain security and store
the directory services database. This arrangement permits central administration
of domain account privileges, security, and network resources. Networked
devices and users belonging to a domain validate with a domain controller at
startup. All computers that refer to a specific set of domain controllers make
up the domain. In addition, group accounts such as global groups and domain
local groups are defined on a domain-wide basis.
