Namespace refers to the naming convention that defines a set of unique names for resources in a network, such as Domain Name System (DNS), a hierarchical naming structure that identifies each network resource and its place in the hierarchy of the namespace, and Windows Internet Name Service (WINS), a flat naming structure that identifies each network resource using a single, unique name.
DNS is required for Active Directory. DNS is a hierarchical, distributed database that contains mappings of DNS domain names to various types of data, such as IP addresses. DNS enables the location of computers and services by user-friendly names, and it also enables the discovery of other information stored in the database.
When setting up a namespace, it is recommended that you first choose and register a unique parent DNS domain name that can be used for hosting your organization on the Internet, for example, microsoft.com. Once you have chosen your parent domain name, you can combine this name with a location or organizational name used within your organization to form other subdomain names. For example, if a subdomain were added, such as itg.example.microsoft.com domain tree (for resources used by the information technology group at your organization), additional subdomain names could be formed using this name. For instance, a group of programmers working on electronic data interchange (EDI) in this division could have a subdomain named edi.itg.example.microsoft.com. Likewise, another group of workers providing support in this division might use support.itg.example.microsoft.com.
Prior to beginning the upgrade from Windows NT Server 4.0 to the Windows Server 2003 Active Directory service, ensure that you have designed a DNS and Active Directory namespace and have either configured DNS servers or are planning to have the Active Directory Installation Wizard automatically install the DNS service on the domain controller.
Active Directory is integrated with DNS in the following ways:
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Active Directory and DNS have the same hierarchical structure. Although separate and implemented differently for different purposes, an organization's namespace for DNS and Active Directory have an identical structure. For example, microsoft.com is both a DNS domain and an Active Directory domain.
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DNS zones can be stored in Active Directory. If you are using the Windows Server DNS service, primary zone files can be stored in Active Directory for replication to other Active Directory domain controllers.
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Active Directory uses DNS as a locator service, resolving Active Directory domain, site, and service names to an IP address. To log on to an Active Directory domain, an Active Directory client queries its configured DNS server for the IP address of the Lightweight Directory Access Protocol (LDAP) service running on a domain controller for a specified domain. For more information on how Active Directory clients rely on DNS, see “Locating a Domain Controller” in the Windows Server 2003 on-screen Help and Support Center.
While Active Directory is integrated with DNS and they share the same namespace structure, it is important to distinguish the basic difference between them:
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DNS is a name resolution service. DNS clients send DNS name queries to their configured DNS server. The DNS server receives the name query and either resolves the name query through locally stored files or consults another DNS server for resolution. DNS does not require Active Directory to function.
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Active Directory is a directory service. Active Directory provides an information repository and services to make information available to users and applications. Active Directory clients send queries to Active Directory servers using LDAP. In order to locate an Active Directory server, an Active Directory client queries DNS. Active Directory requires DNS to function.
For more information on DNS configuration, see the Windows Server 2003 on-screen Help and Support Center.
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