Your company wants to monitor their Azure VMs and collect data from the guest OS. Which Azure Monitor agent should they use?

The Azure Diagnostics extension is specifically designed to gather diagnostic data from the guest operating system of Azure Virtual Machines. By using this extension, companies can collect a wide range of metrics and logs related to system performance, application behavior, and other insights from the VM itself, thereby enabling effective monitoring and troubleshooting.

This tool integrates seamlessly with Azure Monitor, allowing the collected data to be sent to Azure Monitor services or other storage solutions where it can be analyzed and acted upon. The Azure Diagnostics extension's capability to provide deep visibility into the VM's operational perspective makes it extremely valuable for comprehensive monitoring efforts.

In contrast, while Azure Active Directory provides identity and access management, it does not facilitate monitoring or data collection from VMs. Azure Security Center is focused on security posture management and threat protection rather than direct monitoring of the guest OS. The Azure Monitor Agent, which has emerged as the successor to the Azure Diagnostics extension, is also a suitable choice for collecting telemetry data but may not be the designated option for gathering insights specifically from the guest OS as per the terms of the question. Therefore, the Azure Diagnostics extension is the most appropriate choice for collecting VM guest OS data in this context.