• MCS VDA registration fails consistently after rejoining the VDAs to the Domain
• Other VDAs which aren't removed from the Domain register successfully

1. Delete the machines from the Delivery Group, Machine catalog, and  VDA's AD computer object as well
2. Add a new VDA to the same Machine catalog and Delivery group, which would create a VDA with the name as per the sequence set on the Machine catalog OR
3. If you would like to use the same hostname/FQDN of the VDA, reset the MCS counter as per https://support.citrix.com/article/CTX217233/reset-the-start-count-of-mcs-catalog-after-the-catalog-has-already-been-created and add a new machine to same Machine catalog and Delivery group

Problem Cause

Rejoining the VDA to the domain is unsupported for the MCS VDAs. This results in issues like deregistration and add domain-related challenges as MCS VDAs Domain object is expected to be created by the DDCs