High availability
IoT Hub is a platform as a service (PaaS) offering from Azure. Customers and users do not directly interact with the underlying number and size of virtual machines on which the IoT Hub service runs. Users decide on the region, the SKU of the IoT hub, and the number of units for their application. The rest of the configuration is determined and executed by Azure behind the scenes. Azure ensures that every PaaS service is highly available by default. It does so by ensuring that multiple virtual machines provisioned behind the service are on separate racks in the datacenter. It does this by placing those virtual machines on an availability set and on a separate fault and update domain. This helps ensure high availability for both planned and unplanned maintenance. Availability sets take care of high availability at the datacenter level.
In the next section, we will discuss Azure IoT Central.