/online : Tells the tool to make changes to the operating system currently running.
: Once you mount the ISO or plug in your USB installer, navigate to: D:\sources\sxs\ (Replace D: with your specific drive letter). Download Microsoft-windows-netfx3-ondemand-package.cab
Dism /online /enable-feature /featurename:NetFX3 /All /Source:D:\sources\sxs /LimitAccess Use code with caution. /online : Tells the tool to make changes
: Right-click the Start button and select Command Prompt (Admin) or Windows PowerShell (Admin) . Download Microsoft-windows-netfx3-ondemand-package.cab
/LimitAccess : Prevents DISM from trying to contact Windows Update.