User guide

Glossary 258
domain controller (Windows 2000 and Windows Server 2003)
A Windows® 2000-based server with active directory installed and enabled. The act of installing and
enabling active directory necessarily causes a platform to become a domain controller. Each domain
controller holds a single domain. A single domain controller cannot host more than one domain. See also
Peer Master Domain Controller.
Domain Mode
See Mixed Domain Mode, Native Domain Mode, and functional levels.
Domain Name System
The DNS is a hierarchal distributed database used for name/address translation. DNS is the name space
used on the Internet to translate computer and service named into TCP/IP addresses. Active directory uses
DNS as its location service, and so clients find domain controllers using DNS queries. Active directory
can be used to hold the data (for example, zone and forwarding records) that constitutes the DNS
database used by the DNS service running on the domain controller. When DNS records in a Domain
Controller are held in its active directory database, DNS zone transfers are handled as active directory
replication operations and DNS and active directory are said to be "tightly integrated."
domain tree
See domain.
domain tree root
The first domain created in a domain tree. It might not be the forest root.
forest
A group of one or more active directory domain trees that mutually trust each other. All domain trees in a
forest share a common schema, configuration, and global catalog. Each tree has a root domain and zero
or more descendent domains, forming a contiguous name space. When a forest contains multiple trees,
the trees collectively do not form a single contiguous name space. All trees in a given forest trust each
other though transitive bidirectional trust relationships. Unlike a domain tree, a forest does not need a
distinct name. However, the root of the first tree created in the forest is always referred to as the root of
the forest. A forest exists as a set of cross-referenced objects and trust relationships known to all member
trees. See also domain and forest root.
forest root
The first domain created in an active directory deployment. After the first domain is created, additional
domains can be created as child domains of that root and/or as new roots of additional trees in the same
forest within an enterprise active directory deployment. See also forest, domain tree root, and domain.
functional levels (Windows Server™ 2003)
Windows Server™ 2003 expands on the domain mode concept introduced in Windows® 2000 (see
Mixed Domain Mode and Native Domain Mode). Functional levels apply to both forests and domains.
Like the domain mode, functional levels limit what type of operating systems can run on domain
controllers in a domain or forest. Each functional level also has an associated list of features that become
available when the domain or forest reaches that particular functional level. Functional levels become
relevant in a domain and forest when the first domain controller running Windows Server™ 2003 is
added to a domain. By default the domain functional level is set to "Windows 2000 Mixed," and the
forest functional level is set to "Windows 2000." Functional levels can be set using the ADUC snap-in.