After installation of client version try to create a new ODBC connection.
and use it in your QV.
Control panel-->Administrative tools-->Data source ODBC--> create a new ODBC connection for your Oracle database.
else check with Database admin team weather the server is UP or not? some times due to N/w issue also Timeout issue will come.
Question: I'm getting the error "ORA-12170: TNS:Connect timeout occurred" when I try to connect to my database via OEM. How do I resolve the "ORA-12170: TNS: Connect timeout occurred" error?
Answer: The ORA-12170 error can be for many reasons, firewall issue, database down, listener down, bad sqlnet.ora parm, network trouble, etc. The docs note:
ORA-12170: TNS:Connect timeout occurred
Cause: The server shut down because connection establishment or communication with a client failed to complete within the allotted time interval. This may be a result of network or system delays; or this may indicate that a malicious client is trying to cause a Denial of Service attack on the server.
Action: If the error occurred because of a slow network or system, reconfigure one or all of the parameters SQLNET.INBOUND_CONNECT_TIMEOUT, SQLNET.SEND_TIMEOUT, SQLNET.RECV_TIMEOUT in sqlnet.ora to larger values. If a malicious client is suspected, use the address in sqlnet.log to identify the source and restrict access. Note that logged addresses may not be reliable as they can be forged (e.g. in TCP/IP).
Your sqlnet.ora file can be found in your $ORACLE_HOME/network/admin directory.
ORA-12170 and hosts file
Verify that your /etc/hosts file has a DNS entry:
In Windows XP, make your hosts file is located at win/system32/driver/etc/ and on UNIX, Linux, check /etc/hosts.