Objective 1.2Critical Priority8 min read

Physical Security Mechanisms

Physical barriers and access control mechanisms designed to prevent, deter, or delay unauthorized physical access to facilities and assets. Includes bollards, access control vestibules (mantraps), fencing, locks, and security guards.

Understanding Physical Security Mechanisms

Physical security mechanisms are the tangible barriers that protect facilities, equipment, and people. Before an attacker can compromise your network, they might try to physically access your server room. Physical mechanisms stop or slow them down.

These mechanisms work through three approaches: • Prevent — Make entry impossible (locks, reinforced walls) • Deter — Discourage attempts (visible guards, warning signs) • Delay — Slow attackers, giving time for response (multiple barriers)

Physical security is often the first line of defense. All the cybersecurity in the world doesn't help if someone can walk into your data center and steal a server.

Why This Matters for the Exam

Physical security appears throughout the Security+ exam, both as a standalone topic and integrated into other scenarios. Questions might ask about preventing tailgating (mantraps), protecting against vehicle attacks (bollards), or selecting appropriate physical controls for a facility.

Understanding physical mechanisms also helps with defense-in-depth questions. Physical security forms a layer that complements technical and operational controls—a comprehensive security program includes all three.

Data center security questions frequently involve physical mechanisms. Knowing the purpose of each barrier type helps you answer scenario-based questions about facility protection.

Deep Dive

Bollards

  • •Sturdy posts designed to stop vehicle access while allowing pedestrian traffic.

• Purpose: Prevent vehicle ramming attacks • Types: - Fixed bollards (permanent installation) - Retractable bollards (can be lowered for authorized vehicles) - Removable bollards (can be taken out when needed) • Placement: Building entrances, pedestrian areas, vehicle barriers • Material: Steel, concrete, reinforced materials

*Exam tip:* Bollards protect against vehicle-borne attacks, not pedestrian intrusion.

Access Control Vestibules (Mantraps)

  • •A secure entry system with two doors—only one can open at a time.

• Purpose: Prevent tailgating and piggybacking • How it works: 1. Person enters first door, it closes and locks 2. Authentication required in the vestibule 3. If authenticated, second door unlocks 4. Both doors are never open simultaneously • Features: Weight sensors, video verification, authentication devices • Usage: Data centers, secure facilities, bank vaults

*Key term note:* CompTIA now uses "access control vestibule" instead of "mantrap."

Fencing

  • •Perimeter barriers to define boundaries and deter entry.
HeightSecurity LevelPurpose
3-4 ftPsychological deterrentMarks boundary, deters casual entry
6-7 ftDeters most intrudersMakes climbing difficult
8+ ft with barbed wireHigh securitySerious barrier, delays determined attackers

Fencing Features:

  • •Chain link, wrought iron, solid panels
  • •Anti-climb features (barbed wire, razor wire)
  • •Anti-dig barriers (concrete base, mesh below ground)
  • •Clear zone on both sides for visibility

Security Guards

  • •Human presence for access control, monitoring, and response.

• Functions: - Verify identification - Monitor for suspicious activity - Respond to incidents - Deter through visible presence • Types: - Contract guards (outsourced) - Proprietary guards (employees) • Considerations: - Training requirements - Background checks - Authority limitations

Locks

  • •Mechanisms to restrict physical access.

Types:

  • •Key locks — Traditional mechanical locks
  • •Combination locks — Require code knowledge
  • •Cipher locks — Keypad entry with codes
  • •Smart locks — Electronic, can log access
  • •Biometric locks — Fingerprint, retina access

Lock Strength:

  • •Pin tumbler, deadbolts, high-security cylinders
  • •Grade ratings (Grade 1 highest commercial)

Additional Physical Mechanisms

Turnstiles

  • •One person at a time entry
  • •Prevents unauthorized follow-through
  • •Common in lobby areas

Doors and Walls

  • •Fire-rated doors
  • •Reinforced frames
  • •Vault doors for high-security areas

Lighting

  • •Adequate illumination deters intruders
  • •Eliminates hiding spots
  • •Supports surveillance effectiveness

Cable Locks

  • •Secure laptops and equipment
  • •Prevent opportunistic theft

How CompTIA Tests This

Example Analysis

Scenario: A data center experiences incidents where unauthorized individuals follow authorized employees through the entrance. Management needs a solution that ensures only one authenticated person enters at a time.

Analysis: The solution is an access control vestibule (mantrap): • Prevents tailgating by allowing only one person at a time • Both doors cannot be open simultaneously • Authentication required in the vestibule • Weight sensors can detect multiple people

Why other options don't work: • Standard doors can't prevent tailgating • Turnstiles can be jumped over • Guards can be distracted or deceived • Mantraps provide mechanical enforcement

Key insight: The scenario describes "tailgating"—unauthorized entry by following authorized users. Mantraps are specifically designed to prevent this.

Key Terms to Know

physical security mechanismsbollardsmantrapaccess control vestibulefencingsecurity guardsphysical barrierslocks

Common Mistakes to Avoid

Confusing bollards with barriers for people—bollards stop VEHICLES, not pedestrians. They're designed for vehicle ramming attacks.
Using "mantrap" on the exam—CompTIA now uses "access control vestibule." Know both terms but prefer the newer one.
Thinking guards are a complete solution—guards can be deceived, distracted, or absent. They're most effective combined with physical mechanisms.
Forgetting that physical security has grades—not all fencing is equal, not all locks are equal. Higher security requires stronger mechanisms.

Exam Tips

Tailgating/piggybacking → Access control vestibule (mantrap). This is the primary mechanism for preventing unauthorized entry behind authorized users.
Vehicle attacks → Bollards. Protecting building entrances from ramming requires bollards, not fences.
Fence height matters: 3-4 ft = deterrent, 6-7 ft = moderate security, 8+ ft with additions = high security.
Guards are physical controls (not operational in CompTIA's classification) because they provide physical security presence.
Access control vestibule = Both doors never open at same time + Authentication inside = One authenticated person at a time.

Memory Trick

"Physical Security = BFLGS"

  • •Bollards (stop vehicles)
  • •Fencing (perimeter barrier)
  • •Locks (access restriction)
  • •Guards (human presence)
  • •Special entry (vestibules/mantraps)

Tailgating Defense: TAILGATE → TRAP (Mantrap/Vestibule) If someone is following through doors, trap them in a vestibule.

Bollards Memory: BOLLards Block BOLLding from vehicles (Posts that protect buildings from cars/trucks)

  • •Fence Height Rule:
  • •4 ft = "Please don't" (psychological)
  • •7 ft = "You shouldn't" (moderate)
  • •8+ = "You can't" (high security)

Test Your Knowledge

Q1.What physical security mechanism is specifically designed to prevent tailgating at secure entrances?

Q2.An organization needs to protect a building entrance from vehicle ramming attacks while still allowing pedestrian access. Which mechanism should be installed?

Q3.Which fence height provides primarily psychological deterrence without significant physical barrier?

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