tnsping fails, yet sqlplus connects

Oracle 10.2.0.1.0 on Windows 2003 server

While chasing down a problem with a db link, I ran across this bit of strangeness. Our temp hired gun -- who is far better than me -- can't explain it either, beyond a vague comment about differences in Windows....

I've solved my orginal problem, but this bit leaves me with unanswered questions. Here is a short, concise demo, copied straight from the command window. Only the userid and password have been masked. Nothing else has been cut or ortherwise edited.

<==== begin quote ====>

C:\>tnsping epspd

TNS Ping Utility for 32-bit Windows: Version 10.2.0.1.0 - Production on 29-JUN-2
006 09:10:21

Copyright (c) 1997, 2005, Oracle. All rights reserved.

Used parameter files:

TNS-03505: Failed to resolve name

C:\>sqlplus myuser/*****@epspd

SQL*Plus: Release 10.2.0.1.0 - Production on Thu Jun 29 09:10:41 2006

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

SQL>
<==== end quote ====>

FWIW, here's the TNSNAMES entry, witht the IP masked.

EPSPD =
  (DESCRIPTION =
(ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.xxx.xxx.xxx)(PORT = 1521))     )
(CONNECT_DATA =

      (SERVICE_NAME = EPSPD)
    )
  )

My expectation is that if TNSPING fails, so should an actual connection attempt from the same envrionment. Received on Thu Jun 29 2006 - 09:22:17 CDT