Which feature allows for maintenance windows when updating the Azure Virtual Desktop agent?

The correct feature that allows for maintenance windows when updating the Azure Virtual Desktop agent is Scheduled Agent Updates. This feature gives administrators the ability to define specific times when updates can be applied, minimizing interruptions for end users and ensuring that updates occur during off-peak hours or designated maintenance periods.

By leveraging Scheduled Agent Updates, organizations can maintain their Azure Virtual Desktop environment efficiently without affecting user productivity. This feature is particularly useful in scenarios where user availability is critical, allowing updates to be postponed until a specified time.

In contrast, the other options focus on different aspects of Azure Virtual Desktop management. For example, Diagnostic settings provide insights and monitoring capabilities but do not directly handle update scheduling. Drain mode is related to managing active sessions during maintenance but does not control the timing of updates. Finally, scaling plan configuration deals with resource scaling rather than the management of update schedules. These distinctions illustrate the unique purpose of Scheduled Agent Updates in facilitating structured and hassle-free updates.