Resolution: In TRA 5.5 we are shipping DataDirect 3.6 drivers, of which jdbc drivers can be used to work with Oracle 10g R2 and RAC according to DataDirect 3.6 website.
I've located the below link on the internet: http://media.datadirect.com/download/docs/jdbc/jdbcref/title.htm
Please refer to Support for Oracle RAC clause of The Oracle Driver section, in The DataDirect Connect® for JDBC™ User's Guide and Reference.