CEH Social Engineering and Physical Security Practice Question
Which TWO of the following are effective physical security controls to prevent tailgating?
⚠ Common exam trap
Test-takers frequently confuse 'preventive' controls (like mantrap and turnstile) with 'detective' controls (like CCTV) or 'deterrent' controls (like security guards), leading them to select CCTV or guards as effective tailgating prevention measures.
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
✓
Mantrap
A mantrap is a physical security control consisting of two interlocking doors that create a small vestibule. Only one door can be opened at a time, and the system verifies that only one person enters before allowing the second door to open. This design directly prevents tailgating by trapping unauthorized individuals who attempt to follow an authorized person through the first door.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Biometric door lock
Why it's wrong here
A biometric door lock primarily functions as an authentication mechanism, verifying an individual's identity before granting access. However, it does not inherently prevent 'tailgating' or 'piggybacking,' where an unauthorized person follows closely behind an authorized individual who has just successfully authenticated. The lock opens for the authenticated user, but it lacks a physical barrier to restrict subsequent, unverified entries.
- ✓
Mantrap
Why this is correct
A mantrap is a highly effective physical security control consisting of a small vestibule with two interlocking doors. It is designed to ensure that only one person can pass through at a time; the first door must close and lock before the second door can open. This sequential operation physically prevents tailgating by isolating individuals and enforcing single-person occupancy per access cycle.
- ✗
CCTV cameras
Why it's wrong here
CCTV cameras are a crucial component of a comprehensive security system, primarily serving as a deterrent and a detective control. They provide visual surveillance and record events, which can be invaluable for monitoring, real-time alerts to security personnel, and post-incident forensic analysis. However, CCTV cameras do not physically impede or prevent unauthorized individuals from tailgating an authorized person through an access point.
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Security guard
Why it's wrong here
A security guard represents a human-based administrative or personnel control rather than a physical security device or mechanism. While guards are highly effective for observation, intervention, and enforcing access policies, their presence relies on human vigilance and judgment. They do not provide the automated, mechanical, and consistent physical restriction against tailgating that purpose-built devices offer.
- ✓
Turnstile with one-way access
Why this is correct
A turnstile with one-way access is a mechanical physical barrier specifically engineered to permit only one person to pass through per valid credential or token. Its rotating arms or gates physically block unauthorized follow-through, resetting after each authorized passage. This design effectively enforces single-file entry and prevents tailgating by mechanically impeding subsequent individuals until the mechanism is re-activated.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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