sample tnsnames.ora file

The Oracle installer generally places a sample tnsnames.ora file in your
$ORACLE_HOME/network/admin directory, but you can create tnsnames.ora file by using below template.

Here is a sample tnanames.ora file for a oracle database:

TOTEST =-------------->tns name,it can be any name in my case it is connection from DEV to TEST
  (DESCRIPTION =
    (ADDRESS_LIST
      (ADDRESS = (PROTOCOL = TCP)(HOST = oracle12cdb.techgig.com)(PORT = 1529))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = DEV)
    )