How can control effectiveness be primarily determined?

Control effectiveness is primarily determined by evaluating the test results against the intended objectives of the controls. This means assessing how well the controls are achieving their specific security goals and requirements. By testing and measuring the outcomes of the controls in place, organizations can ascertain if the controls are functioning as intended and whether they mitigate risks effectively.

Understanding the alignment between the control's objectives and the results obtained through testing is crucial. If the control is designed to prevent unauthorized access, for example, the effectiveness can be determined by reviewing the results of tests that simulate unauthorized attempts and analyzing how successfully the control thwarted those attempts.

In the context of other options, while knowing if a control is preventative, detective, or compensatory provides important context, it does not directly measure the effectiveness of how well that control performs its intended function. Similarly, the capability of providing notification of failure is significant for monitoring but does not directly equate to effectiveness. Lastly, while evaluating and analyzing reliability is important for ensuring ongoing functionality, it is more about consistency than directly measuring the control's success against its objectives. Therefore, the primary measure of control effectiveness centers on the test results aligning with the intended objectives.