This connection parameter is used to set the MYSQL_DEFAULT_AUTH option of mysql client library. This option was added in MySQL 5.5.7, thus this connection string parameter has an effect only if Direct is set to false and a client library with version 5.5 or higher is used.
This option may be omitted because the client may receive the name of the authentication plugin when performing handshake, but you may use this option to shorten client/server negotiation and avoid a round trip in the protocol.
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2