A control test reveals a 100% pass rate for a detective control. What does this indicate?
Pass rate indicates effective detection.
Why this answer
A 100% pass rate for a detective control indicates that every time the control was tested, it successfully detected the condition or event it was designed to identify. This demonstrates the control is operating effectively, meaning it is functioning as intended and providing the expected level of assurance. For example, if the detective control is an intrusion detection system (IDS) that correctly alerts on all test attack patterns, a 100% pass rate confirms its detection logic and signature updates are working correctly.
Exam trap
The trap here is that candidates often confuse a control's effectiveness (pass rate) with risk mitigation, assuming a perfect detection rate means the risk is fully addressed, but detective controls only provide visibility, not prevention or reduction of risk likelihood.
How to eliminate wrong answers
Option B is wrong because a 100% pass rate does not provide any information about the cost of maintaining the control; cost is a separate consideration related to cost-benefit analysis, not operational effectiveness. Option C is wrong because a 100% pass rate on a detective control does not imply it is compensating for other weaknesses; compensating controls are typically preventive or detective controls that address gaps in primary controls, and a high pass rate alone does not indicate such a relationship. Option D is wrong because a 100% pass rate on a detective control does not mean the associated risk has been fully mitigated; detective controls only identify incidents after they occur, they do not prevent or reduce the likelihood of the risk, and full risk mitigation would require preventive controls or risk acceptance.