Installing .NET Framework 3.5 on Windows Server 2012 the quick way with Powershell
When you add the Feature .NET Framework 3.5 through Add Roles and Features Wizard you will get the error message :
“Do you need to specify an alternate source path? One or more installation selections are missing source files on the destination server”
You could specify the alternate source path through the GUI, but you will have to go through the entire wizard again.
The quick way is to do this with Powershell, the only prerequisite you need is the location of the Windows Server 2012 ISO.
Start Powershell as Administrator and run this script
$ImagePath = “\\server_name\windows_server_2012.ISO”
$ISODrive = (Get-DiskImage -ImagePath $ImagePath | Get-Volume).DriveLetter
Write-Host (“ISO Drive is ” + $ISODrive)
$SourcePath = $ISODrive + “:\Sources\sxs”
Install-WindowsFeature NET-Framework-Core –Source $SourcePath
This will mount the ISO, install .NET Framework 3.5 and dismount the ISO.