You are upgrading your single master Windows NT Server 4.0 network to Windows 2000. The existing primary domain controller (PDC) will become part of the new Active Directory forest. Which computer should you upgrade first in order to establish the new Windows 2000 forest root domain correctly?

Introduction / Context:
This question covers the recommended sequence for upgrading a Windows NT 4.0 domain structure to a Windows 2000 Active Directory forest. When transitioning from an NT 4.0 domain to an Active Directory forest, which server you upgrade first determines the initial forest root domain controller. Understanding the importance of the existing primary domain controller is critical.

Given Data / Assumptions:

• You have a Windows NT Server 4.0 single master domain configuration.
• One NT domain will become the root domain of the new Windows 2000 forest.
• The NT 4.0 domain has a primary domain controller (PDC) and possibly backup domain controllers.
• You plan to perform an in place upgrade rather than building a completely new forest from scratch.

Concept / Approach:
In Windows NT 4.0, the PDC holds the writable copy of the Security Accounts Manager database for the domain. When upgrading to Windows 2000 in place, you must first upgrade the PDC of the domain that will become the root domain in the new Active Directory forest. That upgraded PDC becomes the first domain controller in the forest and defines the forest root domain. Backup domain controllers and member servers should be upgraded later according to your migration plan.

Step-by-Step Solution:
Step 1: Identify which NT 4.0 domain will become the root domain in the new forest.Step 2: Identify the primary domain controller in that domain.Step 3: Upgrade that PDC to Windows 2000 Server first so it becomes the first Active Directory domain controller.Step 4: Afterward, upgrade backup domain controllers and other domains as needed.

Verification / Alternative check:
Microsoft migration tools and guides for Windows 2000 emphasise that the PDC of the root domain is upgraded first. This is consistent with the design of NT 4.0 and the way that Active Directory uses upgraded domain controllers to establish forests and domains. The stand alone server does not have the domain database and cannot serve as the initial forest root domain controller without additional steps.

Why Other Options Are Wrong:
Option a uses a stand alone server, which is not a domain controller and therefore does not hold the domain account database. Options b and c refer to domain controllers in child domains, not the domain chosen as the forest root. Option e claims that any member server can be upgraded first, which is incorrect because forest creation is tied to a domain controller, not a member server.

Common Pitfalls:
Some administrators try to upgrade member servers or backup domain controllers first, expecting that Active Directory will automatically reorganise roles. This can result in unexpected topologies or additional work. Following the documented order of upgrading the PDC of the future root domain ensures a clean and predictable forest structure.

Final Answer:
You should first upgrade the primary domain controller in the Windows NT 4.0 domain that will become the root domain in your new Windows 2000 forest.