If you are looking for a "review" of using the microsoft-windows-netfx3-ondemand-package.cab
Installing the .NET Framework 3.5 on Windows Server 2012 R2 often requires a manual "On-Demand" installation because the source files are not pre-installed on the hard drive to save space. 1. Preparation: Locate the Source Files You need the original Windows Server 2012 R2 installation media (ISO or DVD). Server Fault Mount the ISO : Right-click your ISO file and select . Note the drive letter assigned (e.g., Target Folder : The required file ( microsoft-windows-netfx3-ondemand-package.cab ) is located in the \sources\sxs directory of that drive. Super User 2. Method A: Using Command Prompt (Recommended) This is the fastest method and bypasses common GUI errors. Super User Command Prompt as an Administrator. Run the following command, replacing with your actual mounted drive letter: If you are looking for a "review" of
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:\\fileserver\sources\sxs /LimitAccess
To install .NET Framework 3.5 (identified by the package name Copy the contents of the installation media’s sources\sxs
Technical Overview: Installing .NET Framework 3.5 on Windows Server 2012 R2 Introduction To install
No, the CAB file doesn't expire. But a "new" CAB refers to a freshly downloaded copy from a verified Microsoft ISO, rather than a years-old copy that might have been corrupted on your backup drive. Always re-download from a trusted source if you see checksum mismatches.