What is the Azure IoT Hub feature used for implementing an over-the-air firmware update campaign?

The Azure IoT Hub feature that is specifically designed for implementing an over-the-air firmware update campaign is called Automatic Device Management. This feature allows developers to create and manage firmware updates for devices connected to the IoT Hub, ensuring that devices can receive, verify, and apply firmware updates seamlessly.

Automatic Device Management streamlines the process of deploying firmware updates by managing the complexity of the different device types, ensuring they are updated without needing to involve direct user intervention. This feature allows for scheduling, monitoring, and validating the update process, making it easy to handle scaling across a large number of devices with varied firmware requirements.

While the other choices might relate to various aspects of device management in Azure IoT, they do not specifically address the complete functionality needed for over-the-air firmware updates in the same way. For example, Device Twins provide a way to manage and synchronize device states, but they do not handle the actual firmware updates directly. Firmware Update is not a designated feature in Azure IoT Hub; rather, it is part of the overall capability. The Device Direct Method allows developers to call methods on a device, but again, it doesn't give the comprehensive management capabilities necessary for executing firmware updates across multiple devices in a campaign.