What is considered the only 100% effective physical control?

The only 100% effective physical control is the implementation of physical barriers like walls and locks. These barriers physically prevent unauthorized access to a location or sensitive area, ensuring that individuals without the proper clearance cannot enter. While other security measures can significantly enhance security, they may not guarantee absolute protection on their own.

For instance, security camera systems can record activity and help with monitoring, but they do not physically prevent someone from entering a space. Encryption technologies protect data but do not provide physical security measures against intrusions. The presence of security personnel can deter crime and assist in managing security situations, but human factors such as errors or negligence can sometimes compromise effectiveness. Therefore, physical barriers stand as the most reliable means of control, effectively blocking unauthorized access and providing a tangible layer of security.