Many applications uses Microsoft .NET Framework 3.5 as development platform, and thus requires .NET Framework to be installed beforehand, else the installation will request to download and install .NET Framework from Internet. On offline system without Internet access or online server with slow downloading speed, the requirement to download setup files through web may hit the wall – a no go.
Microsoft initially just provides a minimal size dotnetfx35setup.exe download which is a bootstrapper that will still need to download more files via Internet. For users who prefer to perform offline installation or install .NET Framework 3.5 SP1 without waiting for download to complete will have to download and save a copy of full complete standalone or redistributable Microsoft .NET Framework 3.5 SP1 setup installer, which is finally published by Microsoft.
Microsoft .NET Framework 3.5 SP1 (Service Pack 1) is a full cumulative update that contains many new features building incrementally upon .NET Framework 2.0, 3.0, 3.5, and includes cumulative servicing updates to the .NET Framework 2.0 and .NET Framework 3.0 subcomponents. See KB951847 for list of changes and fixed issues in the .NET Framework 3.5 Service Pack 1.
Download full package of Microsoft .NET Framework 3.5 SP1: dotnetfx35.exe (231 MB)
For known issues and release notes, refer to Microsoft .NET Framework 3.5 SP1 Readme.
Update: Download .NET Framework 4