How should we perform Domain merge?

Question

Hello everyone,

I have an environment where I have two domains. Each domain has 4 domain controllers with Windows Server 2016 each. Both the domains are to be merged into one and the DC Servers must be upgraded from Windows Server 2016 to Windows Server 2022. The existing Domain controllers need to be given new IP addresses in the environment. I have a few questions regarding the same:

1. How should the Domain Merging be performed?
2. When should the Domain Controllers be upgraded? before the Domain is merged or after the domain is merged.?
3. What are the considerations required to be made during the AD modernization and domain merging?

Answer 1

Hello Garima Das，

Thank you for posting in Q&A forum.

How should the Domain Merging be performed?

A1: To merge two domains into one, you can use the Active Directory Migration Tool (ADMT) provided by Microsoft. The ADMT allows you to migrate user accounts, groups, and computers from one domain to another while preserving security identifiers (SIDs) and passwords.

Here are the high-level steps to merge two domains using ADMT:

1. Plan the migration: Determine the scope of the migration, identify the resources that need to be migrated, and create a migration plan.
2. Prepare the source and target domains: Verify that the source and target domains meet the prerequisites for the migration and create trust relationships between the domains.
3. Migrate user accounts, groups, and computers: Use ADMT to migrate the user accounts, groups, and computers from the source domain to the target domain.
4. Migrate resources: Migrate other resources such as file shares, printers, and applications to the target domain.
5. Decommission the source domain: Once the migration is complete, decommission the source domain.

**Note:
1.This is a complex process that requires careful planning and execution. It is recommended that you read the ADMT documentation and seek the assistance of a qualified IT professional to ensure a successful migration.

2.Before you do it in production environment, please do more test in lab.**

When should the Domain Controllers be upgraded? before the Domain is merged or after the domain is merged.?
A2: Before you merge the two domains.

What are the considerations required to be made during the AD modernization and domain merging?

A3: See A1. In my opinion, if your 2 domains are target domain and source domain, I recommend that you keep the complex domain (target domain) and recreate all the data of the source domain in target domain instead of migrating /merging the source domain to target domain, which should have a higher success rate than merging the 2 domains, and the risk will be lower, and the complexity ratio is relatively smaller.

I hope the information above is helpful.

If you have any questions or concerns, please feel free to let us know.

Best Regards,

Daisy Zhou

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