All, we have 2 3-node RAC database . production- xp1-a xp1-b xp1-c qa- tp1-a tp1-b tp1-c both xp1-c and tp1-c were added to the cluster last month . and there is database instance webdp running only on xp1-a xp1-b and the same for webdq on tp1-a tp1-b the jdbc url for production is as below url=jdbc:oracle:thin:@ (DESCRIPTION=(FAILOVER=ON)(ADDRESS_LIST=(LOAD_BALANCE=ON)(ADDRESS=(PROTOCOL=TCP)(HOST=xp1-a)(PORT=1685))(ADDRESS=(PROTOCOL=TCP)(HOST=xp1-b)(PORT=1685))(ADDRESS=(PROTOCOL=TCP)(HOST=xp1-c)(PORT=1685)))(CONNECT_DATA=(SERVICE_NAME=WDATA))); and we see some connection everyday fails on the application server . I also see TNS-12514: TNS:listener does not currently know of service requested in connect descriptor error in listener log on xp1-c . why? and also when i do lsnrctl status listneer_xp1-c on xp1-c I do not see the service_name wdata ( while the same on qa shows the service_name qdata on tp1-c even though no instance running for this db in tp1-c ) . what am I missing ? appreciate any suggestions thanks Kart