What is a File DSN?
The purpose of the Windows file DSN (data source name) is to centrally store your database connection information. If you have many Web pages that require database access, this feature enables you to simply reference the path of the file DSN instead of having to provide the database connection details on every page.
For security reasons, the file DSN is kept in a sub-directory of your hosting content directory that cannot be viewed. The file DSN works with ASP and uses ADO to access a database. This directory is named "_dsn" and you can find it at the root of your hosting account.
NOTE: If you use file DSNs with a Linux shared hosting account, they work only with MySQL databases and must connect to a ColdFusion Web site.