App-pool Idle Time-out is the amount of time (in minutes) a worker process will remain idle before it shuts down. A worker process is idle if it is not processing requests and no new requests are received.
Idle Time-out property can be changed in IIS after you RDP into the VM's of Azure, but this is not recommended and remote desktop must be used only for basic troubleshooting. Any changes done on the Virtual Machine manually after RDP will not be persisted.This is because, in the event of any hardware failure or automatic OS upgrade in Azure cloud, Fabric controller will bring down the VM instance and automatically deploy your package on another VM/on the same VM (Virtual machine). If this happens all the changes done manually on the VM will be lost. Therefore the recommended approach is to perform all the operation by code and deploy the package.
You can implement this by using ServerManager class defined in Microsoft.Web.Administration DLL.
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