-extra __full__ - Microsoft-windows-netfx3-ondemand-package.cab

was sweating. It was 2:00 AM, and the legacy accounting software for the firm’s biggest client was flatlining. The error message was a stubborn, familiar ghost: ".NET Framework 3.5 is required."

You need to point the computer to the location of the .cab file. Assuming your Windows ISO is mounted on drive D: and the file is in the standard location, the command is: Microsoft-windows-netfx3-ondemand-package.cab -Extra

So why would someone exclude "Extra"?