The answer is intrusion detection system (IDS) alerts and review of security incident logs. These are correct examples of detective controls because they function after an event has occurred, analyzing system activity or logs to identify unauthorized access, policy violations, or anomalies that have already taken place. In contrast, preventive controls like firewalls or access controls aim to stop incidents before they happen. On the Certified Information Systems Auditor CISA exam, this distinction tests your understanding of the control categories within the IT governance and security frameworks. A common trap is confusing an IDS with an intrusion prevention system (IPS), which is a preventive control; remember that detective controls only alert or log, they do not block. For a quick memory tip, think of the word “detective” as “detect after”—if it identifies a problem after the fact, like reviewing logs or receiving an IDS alert, it is detective.
CISA Protection of Information Assets Practice Question
This CISA practice question tests your understanding of protection of information assets. 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.
Which TWO of the following are examples of detective controls? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Regular review of security incident logs.
Intrusion detection systems (A) and review of security incident logs (C) are detective controls that identify events after they occur.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Firewall rules that block unauthorized traffic.
Why it's wrong here
Firewall rules are preventive controls, not detective.
✓
Regular review of security incident logs.
Why this is correct
Log review is a detective control that identifies past events.
Related concept
Standard ACLs match source addresses.
✓
Intrusion detection system (IDS) alerts.
Why this is correct
IDS detects potential intrusions in real time but is considered detective as it identifies incidents.
Related concept
Standard ACLs match source addresses.
✗
Encryption of sensitive data at rest.
Why it's wrong here
Encryption is a preventive/corrective control protecting data confidentiality.
✗
Access control lists (ACLs) on network devices.
Why it's wrong here
ACLs are preventive controls that permit or deny traffic.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related CISA ACL questions on filtering logic and placement.
Protection of Information Assets — This question tests Protection of Information Assets — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Regular review of security incident logs. — Intrusion detection systems (A) and review of security incident logs (C) are detective controls that identify events after they occur.
What should I do if I get this CISA question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related CISA ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Match each security control to its category.
medium
Why : Controls are classified by function.
Last reviewed: Jun 24, 2026
Question Discussion
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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.
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