Microsoft Knowledge Base Article 246804 contains the following summary and introduction:

SUMMARY

Microsoft Windows 2000 supports Domain Name System (DNS) updates per RFC 2136. By default, this behavior is enabled for Windows 2000 DNS clients.

Depending on the configuration and services that are running on a particular computer, different components perform DNS updates. There is no centralized way, such as a tool or registry keys, to manage the DNS update behavior of all components. This article describes each component and how to modify that particular component's behavior.

The article also discusses how to disable DNS updates in Microsoft Windows Server 2003. By default, client computers that are running Windows Server 2003 have DNS updates enabled.

INTRODUCTION

The following components perform DNS updates:
Dynamic Host Configuration Protocol (DHCP) Client service
These updates apply to all Windows 2000-based computers.
DNS Server service
These updates apply to Windows 2000-based DNS servers only.
Net Logon service
This updates apply to Windows 2000-based domain controllers only.
Remote access client
These updates apply to Windows 2000-based remote access clients only.

Note After you change one of these components by modifying the registry keys that are listed in this article, you must stop and restart the affected services. Sometimes, you must restart the computer. These instances are noted.