How to get TNS connect strings (like tnsping) to check a dblink via a session? I would like to know, if there is any chance to get the currently used TNS connect string, that will be used for a DB-Link from a db-server.

I'm connected to a schema on a database located on any server.
Now, I have some database links, using tnsnames and which are currently not working properly.
I would like to check, which target database is behind this identifier to verify easily, if this can be correct.

If I would have OS access to the db-server, I would be able to read the ./tnsnames.ora or using tnsping.

But the DDL of the dblink just uses the TNSNAME (RDBX in this example):


  CREATE DATABASE LINK "ABC"
     CONNECT TO "RUSER" IDENTIFIED BY VALUES ':1'
     USING 'RDBX';


Of course, I could ask a DBA, but this is not always as easy in our environment and I would like to be able to double-check it myself without having OS-access.
I do not think that is possible. 
Someone or something needs access to the Filesystem to read the tnsnames.ora.
When using the DB-link oracle will get the definition for RDBX from the tnsnames.ora file. This is transparent to the user, so the user will not notice. As @EdStevens suggested I would try to solve the political issues and work with the DBA.
Or, ask the OS-admin to have a look for you.