Updated: November 25, 2009
Applies To: Windows Server 2008 R2
The Domain Name System (DNS) infrastructure consists of DNS servers that run the DNS Server service and DNS clients that run the DNS Client service.
DNS is a system for naming computers and network services that is organized into a hierarchy of domains. DNS naming is used in TCP/IP networks, such as the Internet, to locate computers and services with user-friendly names. When a user enters a DNS name in an application, DNS services can resolve the name to other information that is associated with the name, such as an IP address.
Hierarchy of Managed Entities
A DNS server hosts the information that enables client computers to resolve memorable, alphanumeric DNS names to the IP addresses that computers use to communicate with each other. Most often, the DNS server responds to requests from DNS clients to provide the IP address associated with a host's DNS domain name. DNS servers can also be configured to provide the name of a host when it receives a query containing the host's IP address, and DNS servers can also provide the IP addresses of other servers configured to provide certain services, such as e-mail.
DNS names are organized into a hierarchy of domains, and domains are grouped and managed in zones on the DNS server.
The DNS Server role in Windows Server 2008 combines support for standard DNS protocols with the benefits of integration with Active Directory Domain Services (AD DS) and other Windows networking and security features, including such advanced capabilities as secure dynamic update of DNS resource records.
The DNS Client service is the client component that resolves and caches Domain Name System (DNS) domain names. When the DNS Client service receives a request to resolve a DNS name that it does not contain in its cache, it queries an assigned DNS server for an IP address for the name. If the DNS Client service receives the requested address, it stores the name and address in its cache to resolve future requests without having to query the DNS server. All computers that use DNS to resolve domain names (including DNS servers and domain controllers) use the DNS Client service for this purpose.