The best way to ensure that information system controls are effective is to test them periodically. Testing controls periodically helps to verify that the controls are operating as intended, and that they are aligned with the enterprise's objectives, policies, and standards. Testing controls periodically also helps to identify any gaps, weaknesses, or deficiencies in the controls, and to implement corrective actions or improvements.
Responding promptly to control exceptions, implementing compensating controls, and automating manual controls are good practices, but they are not the best way to ensure control effectiveness. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 3, Section 3.1.1.2, page 1071
1: ISACA Certified in Risk and Information Systems Control (CRISC) Exam Guide, Answer to Question
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