Oracle Database Discussions

I have installed Oracle 11.2.0.1 on Centos 5.5 64-bit in a guest VM with a Windows 7 64 host OS. The Centos OS is running well and the Oracle database that I created is working well locally. However, I am unable to tnsping the database from a client machine. When I attempt to tnsping from a windows machine (with the appropriate tnsname entry), I get TNS-12541: TNS: no listener. When I attempt to tnsping from another Linux enironment (with the appropriate tnsnames entry), I get the following:

$tnsping demo

TNS Ping Utility for Linux: Version 10.2.0.1.0 - Production on 28-JAN-2011 00:36:13

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

Used parameter files:
/u01/app/oracle/product/10.2/db_1/network/admin/sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.74)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = demo)))
TNS-12560: TNS:protocol adapter error


Here is my tnsnames entry from the linux environment from which I am executing the tnsping (192.168.1.74 is definitely the correct IP):

DEMO =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.74)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = demo)
)
)


The SID name is 'demo' and the listener is running. Here is the out put of lsnrctl status:

/home/oracle> lsnrctl status

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 28-JAN-2011 00:26:32

Copyright (c) 1991, 2009, Oracle. All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date 28-JAN-2011 00:04:26
Uptime 0 days 0 hr. 22 min. 6 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /opt/oracle/11.2.0.2/network/admin/listener.ora
Listener Log File /opt/oracle/diag/tnslsnr/demo/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=demo)(PORT=1521)))
Services Summary...
Service "demo.localdomain" has 1 instance(s).
Instance "demo", status READY, has 1 handler(s) for this service...
Service "demoXDB.localdomain" has 1 instance(s).
Instance "demo", status READY, has 1 handler(s) for this service...
The command completed successfully

AND lsnrctl service:

/home/oracle> lsnrctl service

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 28-JAN-2011 00:41:04

Copyright (c) 1991, 2009, Oracle. All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
Services Summary...
Service "demo.localdomain" has 1 instance(s).
Instance "demo", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
LOCAL SERVER
Service "demoXDB.localdomain" has 1 instance(s).
Instance "demo", status READY, has 1 handler(s) for this service...
Handler(s):
"D000" established:0 refused:0 current:0 max:1022 state:ready
DISPATCHER <machine: demo, pid: 3432>
(ADDRESS=(PROTOCOL=tcp)(HOST=demo)(PORT=13848))
The command completed successfully
/home/oracle>


I have to admit to being a bit confused about the 2 separate handlers and the "demoXDB.localdomain"

I have copied the listener.ora file from a similar environment that is working correctly, stopped and restarted the listener, verified my tnsnames entries many times etc. I am wondering if the problem may be related to the fact that this environment is running in a VM. Maybe some special network configuration is required for the VM network adapter - I have resolved many sqlnet issues over the years, but this one has me baffled. Any help is much appreciated.