Application Health Extension, a health monitoring service used for managing and upgrading your scale sets, has rolled out two new health states ("Initializing", "Unknown") for detailed health reporting using Rich Health States.
New "Initializing" and "Unknown" states provides more control and flexibility over when instance repairs and rolling upgrades are performed on the scale set.
Rich Health States also allows you to mark VMs that are reachable but still considered "Unhealthy" by configuring the emitted probe response body on HTTP/HTTPs protocol.
To learn more, visit: Use Application Health extension with Azure Virtual Machine Scale Sets - Azure Virtual Machine Scale Sets | Microsoft Learn