This is an optional exercise.
You will not receive any points for completing it, nor will you be penalized for not completing it.

If you have access to an Oracle server, try the following:

1. Display database links: Go to SQL*Plus and enter select * from all_db_links; to see all links you are allowed to use.
   
2. Find your tnsnames.ora file. On UNIX, look in $ORACLE_HOME/network/admin. On a PC, try c:\orant\network\admin.

The results of this exercise will vary and are particular to the server to which you connected and its topology.