Physical and Environmental Security
Layered physical defenses
Physical security uses the same layered logic as technical security: deter, delay, detect, assess, and respond. CPTED (Crime Prevention Through Environmental Design) shapes the environment itself — lighting, sight lines, natural access control, and territorial reinforcement — to discourage attacks.
- Perimeter: fencing (8 ft with barbed wire deters determined intruders), lighting, bollards, gates.
- Entry: mantraps and turnstiles defeat piggybacking and tailgating; guards handle judgment calls.
- Interior: locks, badge readers, CCTV with recording, motion and glass-break sensors.
- Fire: detection (smoke, heat, flame) plus suppression appropriate to the class of fire.
- Class A — common combustibles; water or soda acid.
- Class B — liquids; CO2, halon substitute, soda acid.
- Class C — electrical; CO2 or a clean agent, never water.
- Class D — combustible metals; dry powder.
Power and environment
Know the terms: a brownout is a prolonged low voltage, a sag is a momentary low voltage, a spike is a momentary high voltage, a surge is prolonged high voltage, and a blackout is a total loss. UPS covers short outages; generators cover long ones.