Decommissioning a windows server 2003 sub/child domain

Hi,

Is there any impact to the primary AD site which is ad2016 if i'm going to demote the win 2003 AD child/sub domain and if i thick "the last domain controller of this domain?"

No there is no impact on parent domain. You have to be sure that is the last domain controller in the child domain before checking this option.

Since this is subdomain with different domain name to primary.

The subdomain will be deleted and the parent domain keep the same name.

*Are my whole entire AD are also be deleted when i thick the "this is the last domain controller for this domain"? *
Yes.
Since the subdomain that we will decommission is not part of new domain which is AD 2016 domain.com

The child domain panay. domain.com will be removed and no part of child domain of the parent domain domain.com

Please don't forget to mark this reply as answer if it help you to fix your issue

Hi,

Thank you so much for posting here.

Thanks Thameur for the provided information. Parent domain and Child domain are different domains. To demote the Child domain, there is no impact on the parent domain.

Below are more information we would like to share with you.

Demoting the last domain controller in a domain requires Enterprise Admins group membership, as this removes the domain itself (if the last domain in the forest, this removes the forest). Server Manager informs you if the current domain controller is the last domain controller in the domain. Select the Last domain controller in the domain check box to confirm the domain controller is the last domain controller in the domain.

For more information, we could refer to:

Demoting Domain Controllers and Domains
https://video2.skills-academy.com/en-us/windows-server/identity/ad-ds/deploy/demoting-domain-controllers-and-domains--level-200-

Best regards,
Hannah Xiong

Thanks for the comments and suggestion. We have finished AD 2003 decommission successfully without any issue on the primary.. This was very helpful