The answer is that a small population size with critical errors is the valid reason for 100% testing instead of sampling. When the population is small, the statistical benefits of sampling diminish, and the cost of testing every item is low relative to the catastrophic impact of missing a single critical error. This decision aligns with a risk-based audit approach, where the auditor prioritizes complete coverage in high-risk areas to eliminate sampling risk entirely. On the CISA exam, this concept tests your understanding of when to override standard sampling techniques—a common trap is assuming 100% testing is always better for high risk, but it is only justified when the population is small enough to make full testing feasible. Remember the memory tip: “Small and critical, test it all—big and stable, sample and call.”
CISA Information System Auditing Process Practice Question
This CISA practice question tests your understanding of information system auditing process. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An organization uses a risk-based audit approach. For a high-risk area, the auditor decides to perform 100% testing instead of sampling. Which of the following is a valid reason for this decision?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The population size is small and errors are critical
When the population is small and errors are critical, 100% testing ensures complete coverage and minimizes risk.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The population size is small and errors are critical
Why this is correct
100% testing is justified for small populations with high severity risks.
Limited time typically leads to sampling, not 100% testing.
✗
The tolerable error rate is high
Why it's wrong here
High tolerable error rate would allow a smaller sample, not 100% testing.
✗
The control is automated and always effective
Why it's wrong here
If control is always effective, testing may be reduced, not expanded.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A practitioner preparing for the CISA exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related CISA OSPF questions on adjacency and route selection.
Information System Auditing Process — This question tests Information System Auditing Process — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The population size is small and errors are critical — When the population is small and errors are critical, 100% testing ensures complete coverage and minimizes risk.
What should I do if I get this CISA question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related CISA OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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Question Discussion
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