Basic DNS Concepts
Updated: May 3, 2010
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
DNS is a distributed database that represents a namespace. The namespace contains all of the information needed for any client to look up any name. Any DNS server can answer queries about any name within its namespace. A DNS server answers queries in one of the following ways:
If the answer is in its cache, it answers the query from the cache.
If the answer is in a zone hosted by the DNS server, it answers the query from its zone. A zone is a portion of the DNS tree stored on a DNS server. When a DNS server hosts a zone, it is authoritative for the names in that zone, which means that the DNS server can answer queries for any name in the zone. For example, a server hosting the zone contoso.com can answer queries for any name in contoso.com.
If the server cannot answer the query from its cache or zones, it queries other servers for the answer.
It is important to understand the core features of DNS, such as delegation, recursive name resolution, and Active Directory–integrated zones, because they have a direct impact on your Active Directory logical structure design.
For more information about DNS and Active Directory, see "DNS and Active Directory" later in this chapter.