Determining Domain Migration Strategies

Examining the Existing Domain Structure

After you have made sure that your current operating system can be upgraded to Windows 2000, your next task is to examine your existing domain structure. To help you understand the concepts being discussed, consider the Windows NT domain structure shown in Figure 10.2. This example is based on a domain design found in many organizations: a multiple-master domain model. This example shows an upgrade that begins with an account domain, which is typically the first domain to be upgraded.

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Figure 10.2 Example Multiple-master Domain Model

Consider the following when you examine your existing Windows NT domain structure:

What type of domain structure do you have?
Your existing domain structure helps determine how to plan your domain upgrade.
Are there any existing trust relationships (one- and two-way) and domains that you do not want to include in the forest?
These Windows NT domains use explicit one-way trusts to connect to the forest. Domains upgraded to Windows 2000 Server and designated as part of the same forest will be connected by transitive two-way trusts. This is why it is important to know which trusts must remain explicit. Note that all trusts existing before the upgrade will be preserved.
How many domain controllers do you have, and where are they located within each domain?
This information will help you project how much effort will be required to upgrade a given domain.
What DNS namespace(s) exist within your organization?
Because you cannot rename domains in Windows 2000, you need to know the existing namespace(s) in use in your organization and what additional namespaces your organization allows so that you can create a unique namespace for the forest.