The Data Source Name is a user friendly name configured in the Data Sources ODBC section of the Windows Control Panel. It is basically a map pointing to the data source, in this case a sql db.
The ip address of a web site is in no way related to a DSN. A web site can be defined by a DNS but not a DSN.
A tool like nslookup can return the IP address if you type in the domain name or can return the domain name if you type in the IP address.