In this short article, we will show you how to properly change an Active Directory domain name from test.com to resource.loc. In fact, it is not the best idea to rename an Active Directory domain. In large and complex AD infrastructure, it is better to migrate users, computers, and servers to a new domain. However, for simple and small AD environments (test, pre-prod, or DMZ ), you can easily rename your AD domain according to this guide

Before you start, make sure that:

• You have an up-to-date backup of your domain controllers;
• Replication works correctly in your domain and there are no critical errors of domain controllers or DNS (How to check Active Directory health);
• There is no Exchange in your domain. You cannot rename an AD domain if Exchange is deployed in it (except for Exchange Server 2003);
• To rename a domain, you need Windows Server 2003 or newer (in my example, the functional level of my AD domain and forest is Windows Server 2016).

First of all, create a DNS zone for your new domain on your current domain controllers. To do it, open the dnsmgmt.msc snap-in, create a new primary Forward Lookup Zone with the name resource.loc and replicate it on all DNS servers in your old test.com domain.

You can create a new DNS zone using PowerShell:

Add-DnsServerPrimaryZone -Name resource.loc -ReplicationScope "Domain" –PassThru

Wait till the new DNS zone is replicated on all DCs.

Run the rendom /list command to generate a Domainlist.xml file with the current AD forest configuration.

Get-Content .\Domainlist.xml

<Forest>
<Domain>
<!-- PartitionType:Application -->
<Guid>6944a1cc-d79a-4bdb-9d1b-411fd417bbbc</Guid>
<DNSname>DomainDnsZones.test.com</DNSname>
<NetBiosName></NetBiosName>
<DcName></DcName>
</Domain>
<Domain>
<!-- PartitionType:Application -->
<Guid>bb10d409-4897-4974-9781-77dd94f17d47</Guid>
<DNSname>ForestDnsZones.test.com</DNSname>
<NetBiosName></NetBiosName>
<DcName></DcName>
</Domain>
<Domain>
<!-- ForestRoot -->
<Guid>b91bcb80-7cbc-49b7-8704-11d41b77d891</Guid>
<DNSname>test.com</DNSname>
<NetBiosName>TEST</NetBiosName>
<DcName></DcName>
</Domain>
</Forest>

Open the Domainlist.xml and replace all old domain names with the new ones:

Notepad .\Domainlist.xml

Save the file and run this command:

rendom /showforest

The command will show the changes to be made in the configuration.

The following command will upload Domainlist.xml with the new configuration of AD partitions to the domain controller with the Domain naming master FSMO role:

rendom /upload

After that, you won’t be able to make changes to the AD forest configuration because it will be locked.

The rendom /prepare command will check the availability of all DCs in the forest and if they are ready to be renamed.

Make sure that the command has not returned any errors.

Waiting for DCs to reply.
The script was executed successfully on mun-dc02.test.com
The script was executed successfully on mun-dc00.test.com
2 servers contacted, 0 servers returned Errors
The operation completed successfully.

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