Active Directory domain consolidation is the process of restructuring an organization’s Active Directory setup to reduce the number of domains. Consolidation is often performed as part of a company reorganization, merger or acquisition, but it is also used to simplify an AD infrastructure that has become unwieldy over time.
Reducing AD domain sprawl offers a wealth of important benefits, including reduced administrative overhead and stronger security against today’s onslaught of identity-based attacks. However, Active Directory domain consolidation is complex and it’s critical to perform it correctly, so careful planning, coordination and technical expertise are essential.
This article explains the drivers and benefits of Active Directory consolidation, outlines the steps in the consolidation process, and then explores some of the native and third-party tools available to help.
Common Drivers for Domain Consolidation
A common reason why organizations have a large number of AD domains is a history of merger and acquisition (M&A) deals. M&As require integrating two or more Active Directory environments, often on a very tight schedule. As a result, IT integration teams often lack the time to carefully plan an optimal AD structure. Instead, they retain all the existing domains and enable users across them to work together using options like trust relationships, synchronization tools or identity federation.
Domain sprawl can happen for other reasons as well. For example, organic business growth and associated restructuring can lead to the creation of new domains.
Whatever the cause, domain sprawl can lead to multiple important issues, including the following:
- Security vulnerabilities — Organizations with multiple domains often have inconsistent security controls across them. Adversaries can abuse weak password policies, excessive user privileges, stale user objects, outdated protocols like NTLM and other vulnerabilities to gain access to the weakest domain and move laterally through the environment.
- Inefficient AD management — Having multiple domains increases IT overhead, since administrators have to provision users, manage groups and maintain accurate information for each domain.
- Lack of standardization — Different domains often have different naming conventions, policies and procedures. This lack of standardization can make it challenging for administrators to troubleshoot issues and ensure compliance with regulatory requirements.
- Performance and scalability issues — Domain sprawl can also lead to slow logon times, replication delays, and difficulties in accommodating organizational growth and other changes.
Benefits of Active Directory Consolidation
Consolidating Active Directory domains helps address the issues associated with domain spawl. Key benefits include the following:
- Improved security — Centralizing user authentication and access control in a single domain can enhance security by simplifying the enforcement of consistent security policies and reducing the potential for security gaps or misconfigurations across domains.
- Simplified management — Consolidation reduces administrative overhead by enabling centralized management of AD user and computer accounts, security and distribution groups, and Group Policy.
- Cost savings — Domain consolidation can reduce hardware, software infrastructure and operational expenses.
- Enhanced user productivity — Active Directory consolidation facilitates seamless collaboration and resource sharing among users.
- Simplified resource access — Users in a consolidated domain have easier access to file servers, printers, applications and other shared resources.
- Scalability and flexibility — Consolidating multiple domains into one allows for easier infrastructure expansion and adaptation to changing business needs.
- Compliance and governance — Consolidation makes it easier to establish and enforce consistent data protection and access control policies as mandated by various regulatory requirements.
The Active Directory Domain Consolidation Process
Assessment
The first step in AD domain consolidation is to carefully evaluate the existing Active Directory domains, including their structure, content and resource access. Be sure to consider the following:
- AD objects — Identify the users, computers and other objects to be migrated, and check for conflicting or duplicate users and groups within and across domains.
- Application compatibility — Review all applications and services that rely on Active Directory authentication and authorization. Ensuring that they continue to function properly after consolidation can be a significant challenge, since changes to the directory structure can impact application integration.
- Security and access control — Understand your current and desired security policies and access controls.
- DNS and network infrastructure — Do you best to proactively identify and address issues related to DNS name resolution, network connectivity and routing that may arise during the consolidation process.
- Communication and training — Identify everyone who will be impacted by the Active Directory consolidation and develop effective communication and training plans. Be sure to factor in potential resistance to change.
Planning and Preparation
Develop a detailed domain consolidation plan, including timelines, resource allocation and communication strategies.
- Choose the target — The target environment can be an existing domain or a new domain in an existing or new forest. While migrating to a new domain is an opportunity to start fresh, it is not necessarily the best choice. If the move is not handled appropriately, it could cause disruptions for both users and apps. For example, the migration can cause changes to users’ security identifiers (SIDs) that can affect access rights, as well as password changes that users must deal with.
- Design the consolidated architecture — Decide on the new organizational unit (OU) structure, Group Policies and related architecture components. Consider current and future security, compliance and auditing needs, as well as your desired IT administration processes.
- Establish trust relationships — Create trust relationships between the source and target domains to enable seamless migration and cross-domain resource access during the consolidation process.
- Create a test environment — Set up a realistic AD environment to test your consolidation plan.
Migration
Execute your consolidation jobs according to your plan. Be sure to cover the following:
- AD objects — Migrate user accounts, groups, computers and other AD objects, along with their associated permissions.
- Resources — Move resources such as file servers, printers and applications to the target domain and reconfigure access permissions as needed.
- Domain controllers — If necessary, migrate domain controllers to the target domain, ensuring that all necessary services and configurations are properly transferred.
Post-migration tasks
After the migration jobs complete, be sure to address the following:
- Validation — Thoroughly test the consolidated domain to ensure that all accounts, resources and permissions are functioning as expected. This may involve conducting user acceptance testing and validating access to critical resources.
- Decommissioning — Once the migration is validated, decommission the source domains and associated domain controllers.
- Monitoring and troubleshooting — Monitor the consolidated domain to ensure everything is functioning correctly, and promptly address any issues that arise.
- Documentation and training — Update documentation to reflect the new AD structure and train staff on the new processes and structure.
Tools for Active Directory Domain Consolidation
Specialized migration tools can streamline the domain consolidate process and minimize disruption to business operations. There are both native and third-party options available.
Active Directory Migration Tool (ADMT)
Microsoft’s ADMT utility facilitates the migration of objects between Active Directory domains. Install ADMT on a dedicated server or workstation that meets the system requirements. Ensure that the account used to run ADMT has the necessary permissions in both the source and target domains. ADMT can help with the following:
- Establishing trust relationships — You can create trust relationships between the source and target domains using ADMT.
- User and computer migration — ADMT can migrate user accounts while preserving passwords, permissions and SID history, which helps ensure a seamless transition for users. ADMT can also migrate computer accounts to transition domain-joined devices.
- Group migration — ADMT can also migrate security and distribution groups, including their permissions and memberships.
- Rollback — ADMT provides the ability to undo migration operations in case of errors or unexpected outcomes.
- Reporting — ADMT provides visibility into the status of migrated objects and any issues.
Third-Party Tools
Below are some well-known third-party tools you can use for Active Directory consolidation:
- Quest On Demand Migration — This SaaS solution enables consolidation and migration of AD domains as well as Office 365 tenants .
- Quest Migration Manager for Active Directory — This tool provides comprehensive capabilities for AD consolidation and restructuring, including pre-migration analysis, automated migration and real-time monitoring.
- Quest Migrator Pro for Active Directory — This tool automates the restructuring, consolidation and separation of Active Directory environments. It synchronizes and migrates objects, settings, properties, workstations and servers within and between AD forests, even if they’re disconnected or are on isolated networks.
- ManageEngine ADManager Plus — This tool provides automation and workflow capabilities to streamline the consolidation process. It also offers a range of features for managing Active Directory environments, including user, group and password management.
Conclusion
Consolidating Active Directory domains is not a simple task, but it can deliver significant benefits, including stronger security, reduced IT overhead, enhanced productivity and collaboration, and cost savings. Investing in a third-party migration solution can simplify the domain consolidation process and help ensure a successful outcome.
To manage the consolidated domain effectively, be sure to implement best practices such as activity monitoring, identity and access management (IAM) and privileged access management (PAM). Be sure to provide regular training for IT administrators to empower them manage Active Directory securely and efficiently.
FAQ
How do I consolidate multiple domains in Active Directory?
Domain consolidation is a complex process that requires careful planning and execution. It’s important to consult with IT professionals or experienced Active Directory administrators to ensure a successful consolidation.
At a high level, the steps in the process are:
- Assess the source and target domains and develop a detailed migration plan.
- Set up trust relationships between the source and target domains.
- Migrate users, groups, computers and other objects from the source domains to the target domain using ADMT or a third-party tool.
- Perform testing to ensure that everything is working as expected.
- Decommission the old domains.
- Monitor the stability and security of the consolidated domain.
Why consolidate Active Directory domains?
Benefits of consolidating Active Directory domains include:
- Reduced IT overhead through centralized administration of users, groups and resources
- Stronger security through central control over accounts, access permissions and Group Policy
- Better collaboration and communication among users and resources across the organization.
- Reduced hardware, software and administrative costs
Is ADMT still used?
Yes, the Active Directory Migration Tool is still used to migrate objects between Active Directory domains in the same or different forests. It can update the security identifiers (SIDs) of migrated objects and maintain user profile information during domain migrations. It’s important to check for the latest version and ensure compatibility with your Active Directory environment.
Can Active Directory have multiple domains?
Yes, an Active Directory forest can have one or more domains. Each domain represents a separate security boundary with its own set of policies and objects. However, all domains within a forest share a common schema, configuration and global catalog. Trust relationships can be established to allow users, groups and resources to be shared between domains in the same forest.
