Limit physical access to servers and network components to a minimum number of people

Putting sensitive equipment together in dedicated rooms (or dedicated technical areas), properly secured against attempts at illegal access, increases the resistance to such security loopholes as require access to hardware: theft, sabotage, making copies, etc.

By properly restricting physical access to sensitive resources, several security risks are mitigated. Most notably, this concerns theft, sabotage, installation of spyware or spy tech, making copies of drives etc.