The Evolution of Microsoft DNS

Windows Server 2003's implementation of Active Directory expands upon the advanced feature set that Windows 2000 DNS introduced. Several key functional improvements were added, but the overall design and functionality changes have not been significant enough to change any Windows 2000 design decisions that were previously made regarding DNS. The following sections describe the functionality introduced in Windows 2000 DNS that has been carried over to Windows Server 2003 DNS and helps to distinguish it from other DNS implementations.

Active DirectoryIntegrated Zones

The most dramatic change in Windows 2000's DNS implementation was the concept of directory-integrated DNS zones, known as AD-integrated zones. These zones were stored in Active Directory, as opposed to in a text file as in standard DNS. When the Active Directory was replicated, the DNS zone was replicated as well. This also allowed for secure updates, using Kerberos authentication, as well as the concept of multimaster DNS, in which no one server is the master server and all DNS servers contain a writable copy of the zone.

Windows Server 2003 utilizes AD-integrated zones, but with one major change to the design. Instead of storing the zone information directly in the naming contexts of Active Directory, it is stored in the application partition to reduce replication overhead. You can find more information on this concept in the following sections.

Dynamic Updates

As previously mentioned, dynamic updates, using Dynamic DNS (DDNS), allow clients to automatically register and unregister their own host records as they are connected to the network. This concept was a new feature with Windows 2000 DNS and is carried over to Windows Server 2003.

Unicode Character Support

Introduced in Windows 2000 and supported in Windows Server 2003, Unicode support of extended character sets enables DNS to store records written in Unicode, or essentially multiple character sets from many different languages. This functionality essentially allows the DNS server to utilize and perform lookups on records that are written with nonstandard characters, such as underscores, foreign letters, and so on.

Note

Although Microsoft DNS supports Unicode characters, it is best practice that you make any DNS implementation compliant with the standard DNS character set so that you can support zone transfers to and from non-Unicodecompliant DNS implementations such as Unix BIND servers. This includes az, AZ, 09, and the hyphen (-) character.