Migrate 2012 R2 to Server 2022

Health Check (first step)

Run dcdiag, repadmin /replsummary, and check DNS, replication, and SYSVOL status.

Fix any replication or DNS errors before starting the migration.

Add New 2022 Domain Controllers

Join the new Server 2022 machines to the domain.

Promote them to Domain Controllers using Server Manager or PowerShell.

Verify replication with existing 2012 R2 and 2016 DCs.

Transfer FSMO Roles

Move all FSMO roles (Schema, Domain Naming, RID, PDC, Infrastructure) to one of the new 2022 DCs:
Move-ADDirectoryServerOperationMasterRole -Identity "NewDC" -OperationMasterRole 0,1,2,3,4

Validate Domain Functionality

Run health checks again (dcdiag, repadmin, netdom query fsmo).

Confirm login, GPOs, DNS, and replication all work normally.

Migrate Other Roles

CA Migration: install Certificate Services on the new server, back up and restore CA database, private key, and configuration.

DHCP Migration: export the DHCP configuration from old servers and import to the new 2022 DHCP servers.

Configure DHCP failover for high availability.

Decommission Old DCs

Once everything is tested and stable, demote the 2012 R2 and 2016 DCs.

Remove them from AD Sites and Services.

Azure DR or Other Sites

Clean up any old DR or remote DCs after confirming replication and authentication work properly on new 2022 DCs.