A security engineer is preparing tools for an engagement with operational technology. Which of the following protocols are most likely part of OT?

Modbus is a communication protocol that plays a significant role in operational technology (OT) environments. It was designed specifically for industrial applications and is widely used in the automation industry for connecting various devices, such as programmable logic controllers (PLCs) and sensors, to supervisory control and data acquisition (SCADA) systems. Its simplicity and effectiveness in facilitating communication between devices on a network make it a staple in OT systems, which often require reliable and straightforward data exchange among disparate components.

In the context of operational technology, Modbus enables real-time monitoring and control, which is crucial for industries such as manufacturing, energy, and utilities. Its open protocol format allows for interoperability among devices from different manufacturers, reinforcing its utility in multi-vendor environments typically found in OT setups.

The other protocols mentioned, while relevant in various contexts within IT and engineering, are not as central or foundational to the core applications found in operational technology. Therefore, Modbus stands out as the protocol most commonly associated with OT, making it the correct choice in this scenario.