The correct answer is A. In Cisco UCS Manager, the Firmware Auto Sync Server Policy is used to keep the firmware on a server aligned with the firmware packages defined in its associated service profile or service profile template. When this policy is enabled, Cisco UCS Manager checks for firmware mismatches and can initiate the synchronization process so the server components move to the expected firmware levels. However, this behavior is still controlled and does not bypass operational safeguards. In normal Cisco UCS firmware workflows, administrator awareness and acknowledgment are required for disruptive actions, especially when activation or reboot may be necessary.

Option B is incorrect because firmware auto sync does not mean the UCS domain becomes active without the required firmware process. Option C is too absolute; a reboot depends on the component and upgrade type, and it is not the defining effect of the auto sync server policy itself. Option D is also incorrect because UCS Manager continues to provide status, faults, and reporting related to firmware operations.

So the key effect of the policy is automatic firmware synchronization, subject to administrative control and acknowledgment, which matches A.