Azure Update Domain
Azure Update Domain is grouping servers that are under scheduled maintenance. If all the virtual machines are kept under maintenance then there will be application downtime and it will affect the usage of end users to avoid these types of mistakes the virtual machine which is under maintenance will be grouped and another virtual machine that is not under maintenance will run continuously.
We need to understand that Azure Fault Domains and Azure Update Domains are both different with different use cases.
Microsoft Azure – What are Regions and Availability Zones
Azure is Microsoft’s cloud infrastructure service. It provides a comprehensive set of technologies that allow you to build, test and deploy your applications using the Microsoft technology stack: Windows Server, SQL Server, System Center, Microsoft Office, and more. Microsoft Azure offers a wide range of tools, such as tools for developers, business professionals, data & analytics users, storage users, and power users.