File with a .DSN extension contains description of source data – name, info on where a specific database can be found, server address and necessary logging data, along with drivers necessary to establish a connection with the database, usually contained in form of text. Database client can also use entries in the Windows register instead of DSN files.

DSN format is utilised by the ODBC application drivers in order to connect with a database, for instance – with an SQL Server or Microsoft Access. Files can be opened with the ODBC Data Source Administrator software, which is a resource of Windows system; one of the managing tools available in the Control Panel or Menu Start programs.