Identifying Server Upgrade Paths for Windows

When installing a Windows 2000 Server edition onto a computer that is running a previous version of Windows, you should upgrade the Primary Domain Controller, rather than install a fresh version of Windows 2000 on that machine.
By upgrading, you retain all of your security and user accounts, which saves you from having to reenter domain- related information, such as computer accounts, user accounts, security groups, shared resources, and any server applications that are installed on that machine.
You should also seriously consider upgrading when a machine is running a server application that requires a great deal of customization.
Exchange Server 5.5 is such an example. You end up saving a lot of time by upgrading rather than performing a fresh install, assuming that the upgrade goes smoothly.
To upgrade domain controllers and member servers running previous versions of Windows NT to Windows 2000 Advanced Server, identify the upgrade paths for server operating systems in the following table.

Many servers running Windows NT 3.1 or Windows NT 3.5 will not have the necessary hardware to run Windows 2000.
To upgrade these servers and preserve the system configuration, you must first upgrade the system hardware to meet the Windows 2000 hardware requirements.
You can then upgrade the operating system to Windows NT 3.51 or Windows NT 4.0, and then to Windows 2000 Advanced Server.
In the next lesson, you will learn how to prev up critical data files and settings.