Do not download this installer from third-party "DLL download" sites or torrents. Many are packed with malware. Always source from Microsoft or a trusted repository (like MajorGeeks, which hosts Microsoft-sanctioned files).
The 4.0 release introduced significant improvements for both developers and end-users: download net framework v4.0.3019 offline installer
Follow the on-screen instructions. Since this is the , you do not need an active internet connection during the installation process. Verification : Do not download this installer from third-party "DLL