The answer is a mantrap, or dual-door interlocking system, because it is the most effective physical security control for preventing tailgating into a data center. This system works by creating a small vestibule with two interlocking doors that cannot open simultaneously, forcing each individual to authenticate and be verified before the second door unlocks. This physical isolation ensures that only one person passes through at a time, making it impossible for an unauthorized person to slip in behind an authorized user. On the Certified Information Systems Auditor CISA exam, this concept tests your understanding of physical access controls and their role in layered security, often appearing in questions about perimeter defenses or data center safeguards. A common trap is confusing a mantrap with a simple turnstile or badge reader, which lack the dual-door isolation mechanism. Remember the mnemonic “Two doors, one person” to recall that a mantrap enforces one-at-a-time entry, directly blocking tailgating attempts.
CISA Protection of Information Assets Practice Question
This CISA practice question tests your understanding of protection of information assets. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 physical security control is most effective for preventing unauthorized individuals from tailgating into a data center?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Mantrap (dual-door interlocking system).
A mantrap, or dual-door interlocking system, is the most effective physical security control against tailgating because it physically isolates individuals in a small vestibule where both doors cannot be opened simultaneously. This forces authentication and verification for each person before the second door unlocks, preventing an unauthorized person from following an authorized individual through a single entry point.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Mantrap (dual-door interlocking system).
Why this is correct
A mantrap requires entry through one door before the second opens, forcing single occupancy and preventing tailgating.
Related concept
Read the scenario before looking for a memorised answer.
✗
Security guards at the entrance.
Why it's wrong here
Guards can challenge, but they are not foolproof; mantrap is a more effective mechanical control.
✗
Closed-circuit television (CCTV) surveillance.
Why it's wrong here
CCTV deters and records but does not physically prevent tailgating.
✗
Biometric fingerprint readers.
Why it's wrong here
Biometrics verify identity but do not stop multiple people from entering authentication booth.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose biometric readers or CCTV because they associate them with high security, but fail to recognize that tailgating exploits the gap between authentication and physical passage, which only a mantrap's interlocking doors can mechanically enforce.
Detailed technical explanation
How to think about this question
A mantrap typically uses electronic interlocking mechanisms, often controlled by a programmable logic controller (PLC) or access control system, that enforce a strict one-person-per-authentication rule. In high-security data centers, mantrap systems may integrate with turnstiles or weight sensors to detect multiple occupants, and some advanced models use optical sensors to verify only one person passes per door cycle. This design directly counters the 'piggybacking' attack vector where an attacker closely follows an authorized user through a single door.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Protection of Information Assets — This question tests Protection of Information Assets — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Mantrap (dual-door interlocking system). — A mantrap, or dual-door interlocking system, is the most effective physical security control against tailgating because it physically isolates individuals in a small vestibule where both doors cannot be opened simultaneously. This forces authentication and verification for each person before the second door unlocks, preventing an unauthorized person from following an authorized individual through a single entry point.
What should I do if I get this CISA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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