Getting "The Network Adapter could not establish the connection"

Getting this error when TEST DataSource in WAS?
The test connection operation failed for data source Oracle JDBC Driver DataSource on server server1 at node RCBCTESTNode with the following exception: java.sql.SQLException: The Network Adapter could not establish the connectionDSRA0010E: SQL State = 61000, Error Code = 20. View JVM logs for further details.


Getting this error on the Log from the JDBC jar?

java.sql.SQLException: The Network Adapter could not establish the connection
        at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:412)
        at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:531)G

1. Connect to the Database using SqlDeveloper using the same jdbc jar file.If it works then there is no issue with the Oracle Database connection. if not , then do not read future, fix the Jar. (check for the version compatibility)

2.  If the application is in a different server then , telnet the Db port from that server.

bash-4.2# telnet 10.0.XX.XXX 1521
    Trying...
    Connected to 10.0.XX.XXX.

if this also works then there is no issue with the firewall settings on your app-server. If not, do not read future , ask your network admin to open the port.

3. still having issues?  :) check your connection URL 10 times again n again. Definitely its wrong.

oracle,datasource

Don D