This is a FAQ on GitHub which has a lot of information about 2016.
If you are interested to find out which version of IIS or OS your Azure App Service is running on, you can check it like this.
- Check in KUDU
- Capture a Fiddler trace
I wrote about KUDU here, just in case you do now know about it.
Check in KUDU
As shown in Figure 1, after logging into KUDU, select the Environment link and you will see the OS Version.
Figure 1, which version of OS / IIS am I running on my Azure App Service
Figure 2, which version of OS / IIS am I running on my Azure App Service
Capture a Fiddler trace
In the response header from the App Service you will see Server: in the Miscellaneous collection that identifies the version of IIS. Knowing the version of IIS you can link it back to the OS version as IIS is released along with the OS. I have a table that defines that here.
As seen in Figure 3, as this is IIS 10, you can conclude you are running on Windows Server 2016.
Figure 3, which version of OS / IIS am I running on my Azure App Service
As seen in Figure 4, as you see IIS 8.0, you can conclude Windows Server 2012.
Figure 4, which version of OS / IIS am I running on my Azure App Service