This is a text description of dbaa.gif.  

This illustration is a flow diagram showing the choices available for database
authentication schemes, depending upon whether you are administering the
database from a remote client or locally from the same machine where the
database resides.

If you are administering the database locally, or from a remote client with a
secure connection, you have the following choices:

1) Operating system authentication 
2) Password file authentication

If you are administering the database from a remote client, and you do not have
a secure connection, then your only choice is to use password file
authentication.