CISA Information System Auditing Process Practice Question
Which of the following is the most reliable form of audit evidence?
⚠ Common exam trap
The trap is confusing observation with reperformance; candidates often assume that watching a control being performed is as strong as performing it themselves, but CISA expects recognition that observation is limited by timing and the Hawthorne effect.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Re-performance of a control by the auditor
Reperformance by the auditor is the most reliable form of audit evidence because the auditor directly executes the control or procedure and observes the outcome, eliminating reliance on the representations or actions of others. This direct, independent verification provides strong evidence about whether the control operates effectively. Inquiry, observation, and inspection are all less reliable because they are indirect or can be manipulated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Re-performance of a control by the auditor
Why this is correct
Re-performance requires the auditor to independently execute the control and observe the outcome, producing evidence generated directly by the auditor rather than by the auditee. This direct, first-hand testing yields the highest reliability, exceeding inspection, observation or inquiry.
- ✗
Inquiry of management about a control
Why it's wrong here
Inquiry yields only management's assertion, which is self-serving and unsupported by independent corroboration, so it ranks lowest in reliability. It is tempting because it is quick and inexpensive, and it would be the correct choice when the objective is to understand a process or identify where to focus subsequent substantive testing.
- ✗
Observation of a control being performed
Why it's wrong here
Observation shows a control performed at one moment, but the auditor's presence alters behaviour and it captures only a single instance, not the population. It is tempting because witnessing execution directly confirms the control exists and operates, making it the right choice when testing whether a specific procedure is actually carried out as designed.
- ✗
Inspection of signed approval forms
Why it's wrong here
Signed approval forms are documentary evidence created and held by the auditee, so they can be altered, backdated or fabricated without independent corroboration. It tempts because signatures imply authorisation and formality, and it would be correct as supporting evidence once corroborated by direct observation or system-generated records.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISACA exam blueprint
This CISA practice question is part of Courseiva's free ISACA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISA exam.