hi all, i have 3 nodes of 9204 RAC under rhel 2.1 SQL> host lsnrctl status LSNRCTL for Linux: Version 9.2.0.4.0 - Production on 19-FEB-2007 10:53:44 Copyright (c) 1991, 2002, Oracle Corporation. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=rac1pub)(PORT=1521))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 9.2.0.4.0 - Production Start Date 19-FEB-2007 08:17:25 Uptime 0 days 2 hr. 36 min. 19 sec Trace Level off Security OFF SNMP OFF Listener Parameter File /u01/app/oracle/product/9.2.0/network/admin/listener.ora Listener Log File /u01/app/oracle/product/9.2.0/network/log/listener.log Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=rac1pub)(PORT=1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=rac1pub)(PORT=8080))(Presentation=HTTP)(Session=RAW)) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=rac1pub)(PORT=2100))(Presentation=FTP)(Session=RAW)) Services Summary... Service "PLSExtProc" has 1 instance(s). Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service... Service "racdb" has 3 instance(s). Instance "racdb1", status READY, has 2 handler(s) for this service... Instance "racdb2", status READY, has 1 handler(s) for this service... Instance "racdb3", status READY, has 1 handler(s) for this service... Service "racdb1" has 1 instance(s). Instance "racdb1", status UNKNOWN, has 1 handler(s) for this service... Service "racdbXDB" has 3 instance(s). Instance "racdb1", status READY, has 1 handler(s) for this service... Instance "racdb2", status READY, has 1 handler(s) for this service... Instance "racdb3", status READY, has 1 handler(s) for this service... The command completed successfully tnsnames.ora on client RACDB = (DESCRIPTION = (ADDRESS_LIST = (LOAD_BALANCE = yes) (FAILOVER = yes) (ADDRESS = (PROTOCOL = TCP)(HOST = rac1pub)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = rac2pub)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = rac3pub)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = racdb) ) ) the problem is: when connect through sqlplus on client (windows), i got error randomly, and can connect randomly too. please help, which configuration I was missed? regards ujang