Microsoft Knowledge Base Article 238369 contains the following summary:

This article describes how to promote or demote a domain controller to a stand-alone server in Windows 2000. Promoting a server to a domain controller is the process of installing Active Directory Services on that server. Demoting a domain controller removes Active Directory and switches to using a local User Accounts System (UAS). Before promoting a server to a domain controller, you must plan your structure to best suit your organizational needs and network topologies. An administrator has the following options when promoting a server to a domain controller:

Installing the first domain controller in a new forest
Installing the first domain controller in a new domain tree
Installing the first domain controller in a new child domain
Installing an additional domain controller in a domain tree
Removing Active Directory from domain controller

The Domain Name System (DNS) service is an integral part of Active Directory for name resolution. DNS defines the Windows 2000 namespace and is very flexible. For additional information about DNS requirements and installation, click the article number below to view the article in the Microsoft Knowledge Base:

237675 Setting Up the Domain Name System for Active Directory

After you plan your configuration and decide which option you will be using during the promotion process, use the steps in the appropriate section below. These sections guide an administrator through the promotion process.