Table Of content 1- Availability Set 3- Fault Domain 2- Update Domain Availability Set Before understanding Availability Set, we have to understand some scenarios that can lead to the virtual machine in Azure being impacted. There are three factors that impact VM on Azure are Unplanned Hardware maintenance Event, Unexpected Downtime, and Planned maintenance event. Unplanned Hardware maintenance Event occurs when the Azure platform evaluated that hardware or a component associated with a physical machine is in a failure condition. When this event occurs, Azure issue an unplanned hardware maintenance event to reduce the impact on the virtual machines hosted on that hardware. Azure uses live migration technology to migrate the Virtual Machine from the failing hardware to a healthy physical machine. It takes a few times to be up. Memory, Open files, and network connections are maintained, but performance might be reduced before/after an event. An Unexpected down