In preparation for duplicating your Oracle Database, configure the network between your source and target Oracle Database instances.

• Adding Static Service to Listener
  Insert a static entry for the standby database in the listener.ora file, and save the file.
• Configuring SQL*Net to Prepare the Auxiliary Instance on the Destination Host
  Add entries for primary and standby databases in tnsnames.ora, and then save the file.
• Checking SQL*Net Configuration