Which Azure service provides support for event ingestion from IoT devices?

The most appropriate service for event ingestion from IoT devices in this context is IoT Hub. This service acts as a central hub for bi-directional communication between IoT applications and the devices it manages. It is specifically designed to connect, monitor, and control millions of IoT devices, providing robust features for device-to-cloud and cloud-to-device messaging.

IoT Hub supports various protocols to facilitate the ingestion of telemetry data and events from devices, making it an ideal choice for handling data from IoT devices efficiently. It provides features such as device registration, device management, and secure communications, which are critical for IoT solutions.

While Cosmos DB, Time Series Insights, and Azure Functions play important roles in the broader IoT ecosystem, they are not primarily meant for direct event ingestion. Cosmos DB is a globally distributed database service designed for storing and querying data, Time Series Insights is used for analyzing time-stamped data efficiently, and Azure Functions provides serverless computing capabilities, allowing you to run small pieces of code in response to events. However, these services complement IoT Hub rather than replace its core functionality in the context of event ingestion.