CISSP Security Architecture and Engineering Practice Question
An organization is implementing a defense-in-depth strategy for a data center. Which THREE of the following are examples of physical security controls that align with layered defense?
⚠ Common exam trap
CISSP often tests control classification — candidates see 'intrusion detection' and 'antivirus' as security controls and incorrectly include them as physical controls, forgetting that physical controls must restrict or monitor physical access to facilities and assets.
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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Card reader at building entrance
Option C (card reader at building entrance) is correct because it is a physical access control that authenticates individuals before they can enter the facility, forming an outer layer of defense. Option D (server cage locks) is correct because locking cages around server racks physically restrict access to the most sensitive hardware, adding an inner layer of protection even after someone has entered the building. Option E (perimeter fencing) is correct because fencing establishes the outermost physical boundary of the data center, deterring and delaying unauthorized entry. Options A (antivirus software) and B (network intrusion detection system) are logical/technical controls, not physical security controls, so they do not belong in this layered physical defense scenario.
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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Antivirus software
Why it's wrong here
Antivirus software is a prime example of a technical or logical control, not a physical one. It operates at the software layer of an endpoint, scanning for malicious code and protecting data integrity and system availability, rather than physically restricting access to a facility or hardware.
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Intrusion detection system on the network
Why it's wrong here
An Intrusion Detection System (IDS) on the network is a technical control designed to monitor network traffic for suspicious patterns or policy violations. While vital for detecting cyber threats and a key component of defense in depth, it does not physically prevent unauthorized access to a building, data center, or server equipment.
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Card reader at building entrance
Why this is correct
A card reader at a building entrance is a definitive physical access control mechanism, serving as a critical layer in a defense-in-depth strategy. It enforces authentication and authorization requirements before granting physical entry to a facility, directly restricting human movement and protecting all assets within from unauthorized personnel.
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Server cage locks
Why this is correct
Server cage locks represent a crucial physical control designed to protect high-value IT assets, such as servers and networking equipment, often located within a data center or secure room. These locks provide an additional layer of physical security, preventing unauthorized individuals from directly manipulating or removing sensitive hardware, even if they have gained access to the broader facility.
- ✓
Perimeter fencing
Why this is correct
Perimeter fencing is a foundational physical control that establishes the outermost boundary of a secure area, acting as the first line of defense in a multi-layered physical security strategy. Its primary purpose is to deter casual intrusion, delay determined attackers, and clearly define the property line, making unauthorized entry more difficult and noticeable.
Go deeper
Related to this question
Learn chapter
Software Development Security
Key term
Access control
Access control is the security practice of determining who or what is allowed to view, use, or enter a resource, and under what conditions.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
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.