If you have access to an Oracle server, try the following:
Display database links: Go to SQL*Plus and enter
select * from all_db_links; to see all links you are allowed to use.
Find your tnsnames.ora file. On UNIX, look in $ORACLE_HOME/network/admin. On a PC, try c:\orant\network\admin.
The results of your search will vary and are particular to the server to which you connected and its topology.
|Owner (DBA_DB_LINKS and ALL_DB_LINKS only)
||The owner of the database link.
||The name of the database link. This is the remote database name and the domain name.
||The username specified in the CONNECT TO clause. NULL if the CONNECT TO clause is not supplied.
|Password (USER_DB_LINKS only)
||The password specified in the CONNECT TO clause. NULL if the CONNECT TO clause is not supplied.
||The SQL*Net connect string to the remote database. This corresponds to the USING clause. NULL if the USING clause is not supplied.
||Date the database link was created.