easyMultiple Choice
CISA Practice Question: Which physical security control is most effective…
Which physical security control is most effective for preventing unauthorized individuals from tailgating into a data center?
⚠ Common exam trap
Test-takers frequently 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.
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
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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.
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 uses two interlocking doors so only one opens at a time, physically preventing a second person from following an authorised entrant through. This directly defeats tailgating, unlike badges, cameras or turnstiles, which detect or deter but do not physically stop it.
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Security guards at the entrance.
Why it's wrong here
Guards verify credentials but cannot physically observe every badge-in simultaneously, so a person following closely behind an authenticated employee still passes. Guards suit lobbies needing judgement calls, visitor escorting or incident response, not the continuous one-person-per-entry enforcement that a mantrap or turnstile provides.
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Closed-circuit television (CCTV) surveillance.
Why it's wrong here
CCTV records events for later review and deterrence; it does not physically prevent someone from following an authorised person through a door. CCTV would be correct as a detective control supporting investigations or monitoring multiple areas, rather than stopping tailgating as it occurs.
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Biometric fingerprint readers.
Why it's wrong here
Fingerprint readers authenticate one person at a time and grant access after verification, so an unauthorised individual following an authenticated person through the opened door is not stopped. Biometrics would be correct for verifying individual identity at an access point, not for detecting simultaneous entry.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.