...OLEDBDAC aims to assist programmers in developing of fast and native database applications whose data source is exposed through OLE DB. OLEDBDAC uses native OLE DB through COM interop to enable data access.
OLEDBDAC does not support OLE DB version 2.5 interfaces. OLE DB Providers that require support for OLE DB 2.5 interfaces will not function correctly with the OLE DB Data Access Components. This includes the Microsoft OLE DB provider for Exchange and the Microsoft OLE DB provider for Internet Publishing.
OLEDBDAC does not work with the OLE DB provider for ODBC (MSDASQL). To access an ODBC data source use the ODBCDAC instead.