You have an Active Directory Domain Services (AD DS) domain that contains the domain controllers shown in the following table.
The domain contains an app named App1 that uses a custom application partition to store configuration data.
You decommission App1.
When you attempt to remove the custom application partition, the process fails.
Which domain controller is unavailable?
To remove a custom application partition in an Active Directory Domain Services (AD DS) domain, the Domain Naming Master must be available. The Domain Naming Master is responsible for making changes to the forest-wide domain naming context, including adding or removing directories, domains, and application partitions. Therefore, if the process of removing the custom application partition fails, it is likely because the Domain Naming Master, which is DC3, is unavailable.
C Domain Naming Master - Must be online when domains and application partitions in a forest are added or removed. https://learn.microsoft.com/en-us/troubleshoot/windows-server/identity/fsmo-placement-and-optimization-on-ad-dcs#more-information
C is the correct answer.
If you’re having trouble removing custom storage used for an app on your domain, you might want to check the server holding the Infrastructure Master FSMO role. The Infrastructure Master is responsible for updating references from objects in its domain to objects in other domains1. It’s also responsible for removing an object from its domain and putting it in another domain during an object move
To remove a custom application partition, the domain controller that plays the role of schema master must be available. Therefore, if the removal process is failing, it is likely that DC1, which is the schema master, is unavailable. I recommend checking the status of the DC1 and making sure it is online and working properly. If DC1 is inaccessible, you need to resolve this issue before you can remove the custom application partition.
Why not option A?
The domain naming master FSMO role holder is the DC responsible for making changes to the forest-wide domain name space of the directory, that is, the Partitions\Configuration naming context or LDAP://CN=Partitions, CN=Configuration, DC=<domain>. This DC is the only one that can add or remove a domain from the directory. It can also add or remove cross references to domains in external directories. https://learn.microsoft.com/en-us/troubleshoot/windows-server/identity/fsmo-roles#domain%20naming