Microsoft still hosts the redistributable, but they hide it well. Use this direct link structure:
The .NET Framework 3.5 SP1 Offline Installer (also known as the "Standalone" or "Full Redistributable") contains all the cab files locally. It does not call home to Microsoft. Once downloaded, you can use it on 100 PCs, on a fresh Windows install, or on a disconnected server. net framework 3.5 sp1 offline installer
File details:
To successfully install this without an internet connection, you must use the Deployment Image Servicing and Management (DISM) tool. You will need access to the Windows Installation Media (ISO file, DVD, or USB drive). Microsoft still hosts the redistributable, but they hide
On these systems, .NET 3.5 SP1 is not a Windows Feature but a regular application. Double-click the offline installer dotnetfx35.exe. Follow the wizard. Reboot if required. To successfully install this without an internet connection,
Note: Windows 7 SP1 includes .NET 3.5 SP1 as part of the OS, but you may need to repair or reinstall it.
Cause: Group Policy is blocking alternate sources, or the CAB file is corrupted.
Fix: Open gpedit.msc (Group Policy Editor). Navigate to Computer Config > Admin Templates > System > Specify settings for optional component installation. Set it to Enabled and check "Download repair content directly from Windows Update instead of..." (Ironically, you need to allow WU as a backup, or disable the policy entirely).