Logon Failure Auditing in ORACLE

We just enabled the Logon Failure Auditing in ORACLE. The steps folowed are as follows.

1. change the parammeter audit_trail=db in initSID.ora or ALTER SYSTEM SET audit_trail=db SCOPE=SPFILE;
2.Restart the db.
3.Connect as sysdba and run the below command.

audit create session whenever not successful;

4.Now failures will be logged in dba_audit_trail table.
5.Details of audit options are available in dba_priv_audit_opts table.