You need to update the Azure Virtual Desktop agent in an infrastructure with 25 session hosts. What should you do?

To update the Azure Virtual Desktop agent across the 25 session hosts, enabling Scheduled Agent Updates is the most effective approach. This feature automates the process of updating the agent on the session hosts according to a specified schedule, ensuring that all hosts receive updates seamlessly and without requiring manual intervention.

When Scheduled Agent Updates are enabled, Azure automatically manages the timing of updates, which reduces the risk of downtime or disruptions for users, as updates occur during predefined maintenance windows. This allows for consistent updates across the infrastructure, keeping all session hosts compliant with the latest features and security improvements.

The other options, while relevant in different contexts, do not directly facilitate the update of the Azure Virtual Desktop agent efficiency. For instance, configuring a scaling plan is related to the management of resources and scaling session hosts based on demand, rather than updating them. Configuring diagnostic settings focuses on monitoring and logging but does not pertain to agent updates. Lastly, enabling drain mode is a manual process to prepare session hosts for maintenance tasks, which is valuable but doesn’t automate the update process itself.

Thus, using Scheduled Agent Updates streamlines the updating process, making it the correct choice for ensuring that the Azure Virtual Desktop agents are kept current across the environment.