Allow me to quote Oracle documentation http://docs.oracle.com/cd/B12037_01/...ments_5005.htm

USING 'connect string'

Specify the service name of a remote database. If you specify only the database name, then Oracle Database implicitly appends the database domain to the connect string to create a complete service name. Therefore, if the database domain of the remote database is different from that of the current database, then you must specify the complete service name.


In regards to the question about TNSNAMES entry.... how in the world could we know what it is? Ask