Final answer:
A nonauthoritative AD restore is used when specific changes to Active Directory need to be reversed without affecting the current state of the rest of the domain, such as restoring a mistakenly deleted user account.
Step-by-step explanation:
A nonauthoritative AD restore is performed when you need to restore Active Directory (AD) objects or data to a state before a recent change or deletion, but without the intention to revert the entire directory to that state. This process is used when specific changes need to be rolled back without disrupting the current state of other objects within the domain that could be affected by a complete authoritative restore. Nonauthoritative restore is commonly used when accidental deletions or modifications occur. For instance, if an administrator accidentally deletes a user account, a nonauthoritative restore can be carried out to bring back that specific account without affecting any other changes that have occurred since the backup was taken.