Quick Answer
The answer is an intrusion detection system (IDS) and CCTV surveillance. Both are examples of detective controls because they identify and record security events after they have occurred, rather than preventing them in real time. An IDS monitors network traffic for suspicious patterns and generates alerts for analysis, while CCTV footage provides a visual record for post-incident review and forensic investigation. On the CISSP exam, this distinction tests your understanding of the three primary control categories—preventive, detective, and corrective—and how they map to security operations. A common trap is confusing CCTV with a preventive control like a guard or a corrective control like an alarm; remember that detective controls focus on logging and evidence, not action. Memory tip: think of a detective arriving at a crime scene—they don’t stop the crime, they collect clues afterward.
This CISSP practice question tests your understanding of security operations. 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?
Access control list
Why wrong: Preventive control.
CCTV surveillance
Detects physical security breaches.
Firewall
Why wrong: Preventive control.
Security awareness training
Why wrong: Directive control.
Intrusion detection system (IDS)
Detects suspicious activity.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
CCTV surveillance
CCTV surveillance is a detective control because it records events for later review, enabling the detection of unauthorized activities after they occur. It does not prevent or deter access in real-time, but instead provides evidence for incident investigation and forensic analysis. This aligns with the detective control category in security operations, which focuses on identifying and logging violations post-facto.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Access control list
Why it's wrong here
Preventive control.
CCTV surveillance
Why this is correct
Detects physical security breaches.
Related concept
Read the scenario before looking for a memorised answer.
Firewall
Why it's wrong here
Preventive control.
Security awareness training
Why it's wrong here
Directive control.
Intrusion detection system (IDS)
Why this is correct
Detects suspicious activity.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is confusing preventive controls (like ACLs and firewalls) with detective controls, as candidates often misclassify any technology that 'monitors' as detective, but ACLs and firewalls are inherently preventive because they block or allow access in real-time, not after the fact.
Detailed technical explanation
Detective controls like CCTV and IDS rely on logging and alerting mechanisms; for example, an IDS uses signature-based or anomaly-based detection to analyze network packets against known attack patterns (e.g., Snort rules) or baseline behavior. In contrast, preventive controls such as firewalls operate at Layers 3 and 4 (or up to Layer 7 in next-gen firewalls) to enforce access policies before any traffic reaches the target. A real-world scenario: CCTV footage can be used to correlate with IDS alerts to confirm a physical breach, demonstrating how detective controls support incident response.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A SOC analyst notices unusual lateral movement in the network at 2 AM. The IR playbook dictates: identify and contain (isolate the affected machine), then eradicate (remove the malware), then recover (restore from backup), then document. Skipping containment before eradication risks the attacker regaining access. Questions like this test the sequence and rationale of incident response phases.
What to study next
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FAQ
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
The correct answer is: CCTV surveillance — CCTV surveillance is a detective control because it records events for later review, enabling the detection of unauthorized activities after they occur. It does not prevent or deter access in real-time, but instead provides evidence for incident investigation and forensic analysis. This aligns with the detective control category in security operations, which focuses on identifying and logging violations post-facto.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
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