Inside Windows® Server 2003

Overview of DNS Domain Structure

Before getting too far into DNS domains, let's deal with the ongoing confusion between Microsoft's use of the word domain and the way the term is used in DNS.

Prior to introducing Active Directory, a Microsoft “domain” was completely different than a DNS domain. A DNS domain defines a namespace, such as Company.com. Resource records for hosts within this namespace are stored in a zone file, often simply called a zone. In classic Windows, a domain defines a security structure. Account records for users, groups, and computers within this security structure are stored in the SAM hive in the Registry.

With the advent of Active Directory, the two territories described by the term domain became synonymous. The security ...