MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 3: ODBC Architecture
Data sources usually are created by the end user or a technician with a program called the ODBC Administrator. The ODBC Administrator prompts the user for the driver to use and then calls that driver. The driver displays a dialog box that requests the information it needs to connect to the data source. After the user enters the information, the driver stores it on the system.
Later, the application calls the Driver Manager and passes it the name of a machine data source or the path of a file containing a file data source. When passed a machine data source name, the Driver Manager searches the system to find the driver used by the data source. It then loads the driver and passes the data source name to it. The driver uses the data source name to find the information it needs to connect to the data source. Finally, it connects to the data source, typically prompting the user for a user ID and password, which generally are not stored.
When passed a file data source, the Driver Manager opens the file and loads the specified driver. If the file also contains a connection string, it passes this to the driver. Using the information in the connection string, the driver connects to the data source. If no connection string was passed, the driver generally prompts the user for the necessary information.