Introduced with SQL Server 2005, the SQL Server Native Client was a single dynamic-link library (DLL) containing both the OLE DB provider and the ODBC driver for SQL Server. Before its release, developers had to use the older SQLSRV32.DLL (ODBC) and SQLOLEDB (OLE DB), which were built on top of the legacy DB-Library.
Failure to update the string will keep the application running on the deprecated binary even if the new driver is installed. sql server native client download