DL_ is the extension for compressed DLL files. These files are created by Makecab to take up less space. Makecab is a Windows utility used for compressing files when creating installation CDs. More information: DL_ files can be created using Makecab syntax: makecab myfile.dll. They can be decompressed to DLL files using: expand myfile.dl_ myfile.dll.
NOTE: Makecab can compress any file. Microsoft Windows commonly handles DL_ files. Microsoft Expand and Microsoft Makecab also handle DL_ files. There are 236 file types with the DL_ extension on various operating systems.
To open a DL_ file, double-click it. If that does not work, the file may not be properly associated with the correct software. Install a program that supports DL_ files. Programs that open DL_ files include Makecab and Microsoft Expand.
When facing problems opening unknown DL_ files, first determine the cause. Verify the file is associated properly. If not, associate the DL_ extension with the proper software in Windows Registry. Many files contain simple text data that can be viewed without dedicated software.
Microsoft Windows
File Expansion Utilities