Microsoft Azure Administrator (AZ104) Complete Practice Exam 2025

Adding a new managed disk to an Azure virtual machine is the action least likely to incur downtime. When a managed disk is added to a virtual machine, Azure allows you to perform this operation in a way that doesn’t require the virtual machine to be stopped or deallocated. The process is designed to be done live, ensuring that the VM continues to operate normally while the new disk is being attached.

In contrast, enabling Desired State Configuration Management and adding a new extension often require the virtual machine to be in a particular state or might involve operations that temporarily disrupt services. Changing the size of the virtual machine typically necessitates stopping the VM, especially if you're scaling up or down in size, leading to unavoidable downtime during that process.

Therefore, when it comes to minimizing disruptions in service, adding a new managed disk stands out as the most seamless operation among the given options.