The correct action is to implement a turnstile that allows only one person per smart card authentication. A turnstile physically enforces a one-to-one ratio between credential validation and passage, rotating only after a valid smart card read and locking immediately after a single person passes, which directly prevents tailgating without introducing delays for authorized users. On the ISC2 Certified in Cybersecurity CC exam, this scenario tests your understanding of physical access controls and the specific role of mantrap alternatives like turnstiles; a common trap is choosing biometrics or video surveillance, which add steps or only detect rather than prevent the breach. Remember that turnstiles are the only solution that mechanically blocks multiple entries per authentication, making them ideal for tailgating prevention in high-traffic areas. A helpful memory tip: think “one card, one spin” to recall that a turnstile ties each credential to a single physical passage.
ISC2 CC Access Controls Concepts Practice Question
This CC practice question tests your understanding of access controls concepts. 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.
A financial firm has a data center with strict access controls. Employees must use smart cards and PINs to enter a mantrapped entrance. Recently, an unauthorized person gained access by following an employee through the mantrapped door (tailgating). The security team reviews logs and finds that the door was opened twice in quick succession, indicating tailgating occurred. The firm wants to implement a solution that prevents tailgating without slowing down authorized access. Which action should they take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement a turnstile that allows only one person per smart card authentication
Option C is correct because a turnstile physically enforces one-person-per-authentication by rotating only after a valid smart card read and allowing a single passage, then locking until the next authentication. This directly prevents tailgating without adding delay, as each authorized user passes through at their own pace without needing additional steps like biometric scans or pre-approval.
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.
✗
Require employees to log access requests in advance
Why it's wrong here
Pre-logging is an administrative control that does not prevent tailgating in real-time.
✗
Install a biometric scanner that requires fingerprint and retina scan
Why it's wrong here
Biometrics adds authentication strength but does not physically prevent tailgating; multiple people could potentially pass after one scan.
✓
Implement a turnstile that allows only one person per smart card authentication
Why this is correct
Turnstiles physically enforce one person per credential, directly preventing tailgating.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the number of security guards at the entrance
Why it's wrong here
More guards can monitor but are not as effective as a physical barrier and may slow entry.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the distinction between detection (e.g., logs, cameras) and prevention (e.g., turnstiles, mantrap doors), so candidates mistakenly choose biometric or procedural options that only detect or deter rather than physically block tailgating.
Detailed technical explanation
How to think about this question
A mantrap typically uses two interlocking doors with a small vestibule; a turnstile replaces this with a single physical barrier that rotates exactly 90 or 120 degrees per authentication, using a mechanical clutch that resets after one rotation. In high-security environments, optical sensors or weight sensors can be added to detect if more than one person passes, but a properly rated turnstile alone meets the requirement without slowing flow, as it operates at the speed of a card tap (under 1 second).
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Access Controls Concepts — This question tests Access Controls Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a turnstile that allows only one person per smart card authentication — Option C is correct because a turnstile physically enforces one-person-per-authentication by rotating only after a valid smart card read and allowing a single passage, then locking until the next authentication. This directly prevents tailgating without adding delay, as each authorized user passes through at their own pace without needing additional steps like biometric scans or pre-approval.
What should I do if I get this CC 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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