A defining characteristic of Industrial IoT (IIoT) devices is their deployment in harsh operational environments, such as manufacturing plants, oil rigs, or outdoor agricultural settings. These locations often expose equipment to extreme temperatures, humidity, vibration, dust, and corrosive materials. Consequently, IIoT devices are commonly "ruggedized"—built with durable, sealed enclosures and components that can withstand these conditions to ensure reliability and longevity. This is in stark contrast to most consumer or commercial IoT devices, which are designed for controlled, indoor environments.

B. Use of standardized protocols: Both IIoT and general IoT ecosystems utilize a mix of standardized protocols (e.g., Wi-Fi, MQTT); this is not a unique characteristic of IIoT.

C. Transmission of small amounts of data throughout the day: This is a common feature of many sensor-based devices across both consumer and industrial IoT domains, not a distinguishing factor for IIoT.

D. Use of proprietary protocols: The use of proprietary protocols is prevalent in both legacy industrial systems and various consumer IoT ecosystems; it is not exclusive to IIoT.

1. Vendor Documentation: Cisco, "The Industrial IoT Networking and Security," White Paper, 2020. Page 4 states, "The industrial environment is harsh. Equipment must be able to withstand wider temperature ranges, humidity, vibration, and electrical noise... Industrial IoT network equipment is ruggedized to meet these requirements."

2. Academic Publication: Sisinni, E., Saifullah, A., Han, S., Jennehag, U., & Gidlund, M. (2018). "Industrial Internet of Things: Challenges, Opportunities, and Directions." IEEE Transactions on Industrial Informatics, 14(11), 4724-4734. Section II-A, "Harsh Environment," discusses that IIoT devices must be "designed to be robust against extreme temperature, humidity, vibration, noise, and dust," which distinguishes them from devices used in more controlled settings. (DOI: https://doi.org/10.1109/TII.2018.2852491)

3. Vendor Documentation: Intel Corporation, "Architecting the Future of Industrial IoT," White Paper, 2019. Page 3 discusses the need for "ruggedized devices" that can operate reliably in demanding industrial environments, highlighting this as a key consideration for IIoT deployments.