.NET Framework run time is a Microsoft product which is used to run the applications made with Visual Studio using this framework. If you read the system requirements of most of modern software for Windows, you will see that most of them require .NET Framework to be installed on the computer so that the application can be installed and run.
So below are the links to download all versions of .Net framework offline installers :
1. Download .NET Framework 1.0
Direct download linkService Pack 3 download link
2. Download .NET Framework 1.1
Direct download linkService Pack 1 download link
3. Download .NET Framework 2.0
Download Link (x86)Download Link (x64)
Service Pack 2 download link