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DUN - Dial Up Network File

What is a DUN file

The file extension DUN has been used in former versions of Microsoft Windows, but you might still encounter them on old (external) hard drives. These files were used by Dial-Up Networking tools to store information about internet connection settings. For quick access of the DUN, a file with the appropriate extension was often stored on the desktop of a user's computer.

DUN files are not being used nowadays as Dial-Up Networking tools have been replaced by other way to connect a computer to the internet. The files store information the modem needs to successfully connect to the internet. This includes the phone number and other modem settings.

Here's a small, but not exhaustive list of programs that can open DUN documents:

  • Microsoft Dial-Up Networking (Windows)
Extension DUN
MIME type application/octet-stream
Useful links