An organization is looking to include mobile devices in its asset management system for better tracking. In which system tier of the reference architecture would mobile devices be tracked?

Tier 0 represents the most critical layer, typically encompassing physical process-level devices such as sensors and actuators in industrial control system architectures, not mobile devices.

Tier 1 covers basic control systems and controllers (such as PLCs and RTUs) that directly manage physical processes, which is not where mobile devices are categorized.

Tier 2 in the reference architecture represents the enterprise zone where standard IT assets reside, including workstations, laptops, mobile devices, and other end-user computing equipment. Mobile devices fall into this tier because they operate at the enterprise network level, connecting to corporate resources for business productivity rather than directly interfacing with control systems or critical infrastructure. Asset management systems track mobile devices at this tier alongside other general-purpose computing endpoints.

Tier 3 (or higher) typically represents the demilitarized zone (DMZ) or external-facing network segments used for internet connectivity and external services, not the tier where mobile endpoints are tracked.