Microsoftwindowsnetfx3ondemandpackagecab Download Server 2012 R2 New Work -

To install .NET Framework 3.5 on Windows Server 2012 R2, you need the microsoft-windows-netfx3-ondemand-package.cab file, which is typically found on the original installation media. Because this feature is a "Feature on Demand," the required files are not pre-cached on the server's local drive and often fail to download automatically via Windows Update. Where to Get the CAB File

If your server is connected to WSUS, it may fail to find the package. You may need to bypass WSUS by adding /LimitAccess to your DISM command or adjusting the Group Policy To install

Download the Windows Server 2012 R2 Evaluation ISO from Microsoft.
Mount the ISO.
Navigate to \sources\sxs\. You will find Microsoft-Windows-NetFx3-OnDemand-Package~31bf3856ad364e35~amd64~~.cab (naming may slightly vary).

Why use the OnDemand CAB?

Windows Server 2012 R2 has a “Features on Demand” model: the OS keeps feature payloads (like .NET 3.5) in a local store only if requested. If the payload is not available locally, the system attempts to download the required files from Windows Update.
In environments without internet access, you must provide the .NET 3.5 payload manually — either by pointing the installer to Windows Server installation media (sources\SxS) or by supplying the Microsoft-Windows-NetFx3-OnDemand-Package.cab extracted from media or downloaded from Microsoft.

/LimitAccess: Prevents the server from trying to download files from Windows Update/WSUS, which often causes the 0x800F0954 error. Option 2: Using Server Manager (GUI) Download the Windows Server 2012 R2 Evaluation ISO

This file contains the portable, offline source for .NET 3.5, allowing installation without mounting the full OS ISO. Why use the OnDemand CAB

Why Do You Need This Specific .cab File?

Before diving into the download process, it is crucial to understand why the .cab file is superior to other installation methods.