Certified Ethical Hacker (CEH) Practice Question

In the Purdue Enterprise Reference Architecture, Level 1-known as the Basic Control layer-hosts the programmable logic controllers (PLCs) that execute real-time control logic for the industrial process. Level 0 contains the actual field devices such as sensors, actuators, motors, and valves. Level 2 provides area supervisory functions such as HMIs and basic historians, while Level 3 supports plant-wide operations and production planning. Because PLCs act as the immediate control interface between the physical process at Level 0 and the supervisory systems at Level 2, they are assigned to Level 1, making that the correct choice.