Quote Originally Posted by dbachief
Another way he can look it up is by looking at the listener.ora file.
Possibly, but no guarantee there either. Are you saying that's a sure fire way, or another possible way?

Code:
# listener.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oracle\product\10.2.0\db_1)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = ORCL)
      (ORACLE_HOME = C:\oracle\product\10.2.0\db_1)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
  )