Microsoft Exchange Server 2007 : Consolidating a Windows 2000 Domain to a Windows Server 2003 Domain Using ADMT (part 1) - Modifying Default Domain Policy on the Target Domain

Consolidating and Migrating Domains Using the Active Directory Migration Tool

The development of Windows Server 2003 coincides with improvements in the Active Directory Migration Tool (ADMT), a fully functional domain migration utility included on the Windows Server 2003 CD. ADMT allows Active Directory and NT domain users, computers, and groups to be consolidated, collapsed, or restructured to fit the design needs of an organization. In regard to Windows 2000 migrations, ADMT provides for the flexibility to restructure existing domain environments into new Windows Server 2003 Active Directory environments, keeping security settings, user passwords, and other settings.

Understanding ADMT Functionality

ADMT is an effective way to migrate users, groups, and computers from one domain to another. It is robust enough to migrate security permissions and Exchange mailbox domain settings; plus, it supports a rollback procedure in the event of migration problems. ADMT is composed of the following components and functionality:

• ADMT migration wizards— ADMT includes a series of wizards, each specifically designed to migrate specific components. You can use different wizards to migrate users, groups, computers, service accounts, and trusts.

• Low client impact— ADMT automatically installs a service on source clients negating the need to manually install client software for the migration. In addition, after the migration is complete, these services are automatically uninstalled.

• SID history and security migrated— Users can continue to maintain network access to file shares, applications, and other secured network services through migration of the SID history attributes to the new domain. This preserves the extensive security structure of the source domain.

• Test migrations and rollback functionality— An extremely useful feature in ADMT is the capability to run a mock migration scenario with each migration wizard. This helps to identify any issues that might exist prior to the actual migration work. In addition to this functionality, the most recently performed user, computer, or group migration can be undone, providing for rollback in the event of migration problems.

Consolidating a Windows 2000 Domain to a Windows Server 2003 Domain Using ADMT

ADMT installs very easily but requires a thorough knowledge of the various wizards to be used properly. In addition, best-practice processes should be used when migrating from one domain to another.

The migration example in the following sections describes the most common use of the Active Directory Migration Tool: an interforest migration of domain users, groups, and computers into another domain. This procedure is by no means exclusive, and many other migration techniques can be used to achieve proper results. Thus, matching the capabilities of ADMT with the migration needs of an organization is important.

1. Using ADMT in a Lab Environment

ADMT comes with unprecedented rollback capabilities. Not only can each wizard be tested first, but the last wizard transaction can also be rolled back in the event of problems. In addition, it is highly recommended that you reproduce an environment in a lab setting and that the migration process is tested in advance to mitigate potential problems that might arise.

You can develop the most effective lab by creating new domain controllers in the source and target domains and then physically segregating them into a lab network, where they cannot contact the production domain environment. The Operations Master (OM) roles for each domain can then be seized for each domain using the ntdsutil utility, which effectively creates exact replicas of all user, group, and computer accounts that can be tested with the ADMT.

2. ADMT Installation Procedure

The ADMT component should be installed on a domain controller in the target domain, to which the accounts will be migrated. To install, follow these steps:

ADMT Domain Migration Prerequisites

As previously mentioned, the most important prerequisite for migration with ADMT is lab verification. Testing as many aspects of a migration as possible can help to establish the procedures required and identify potential problems before they occur in the production environment.

That said, several functional prerequisites must be met before the ADMT can function properly. Many of these requirements revolve around the migration of passwords and security objects, and are critical for this functionality.

Creating Two-Way Trusts Between Source and Target Domains

The source and target domains must each be able to communicate with each other and share security credentials. Consequently, it is important to establish trusts between the two domains before running the ADMT.

Assigning Proper Permissions on Source Domain and Source Domain Workstations

The account that will run the ADMT in the target domain must be added into the Builtin\Administrators group in the source domain. In addition, each workstation must include this user as a member of the local Administrators group for the computer migration services to be able to function properly. Domain group changes can be easily accomplished, but a large workstation group change must be scripted, or manually accomplished, prior to migration.

Creating Target Organizational Unit (OU) Structure

The destination for user accounts from the source domain must be designated at several points during the ADMT migration process. Establishing an OU for the source domain accounts can help to simplify and logically organize the new objects. These objects can be moved to other OUs after the migration and this OU can be collapsed, if you want.

Modifying Default Domain Policy on the Target Domain

Unlike previous versions of Windows operating systems, Windows Server 2003 does not support anonymous users authenticating as the Everyone group. This functionality was designed in such a way as to increase security. However, for ADMT to be able to migrate the accounts, this functionality must be disabled. When the process is complete, the policies can be reset to the default levels. To change the policies, follow these steps: