-->再次tnsping时，收到TNS-12547错误
C:\>tnsping demo92
TNS Ping Utility for 32-bit Windows: Version 11.2.0.1.0 - Production on 25-JUN-2011 19:01:21
Copyright (c) 1997, 2010, Oracle. All rights reserved.
Used parameter files:
d:\app\Robinson\Oracle_client\product\11.2.0\client_1\network\admin\sqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 10.103.11.20
9)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = demo92)))
TNS-12547: TNS:lost contact
-->下面的演示中如果excluded_nodes与invited_nodes都存在，则invited_nodes优先，不再演示
[oracle@test admin]$ more sqlnet.ora
# SQLNET.ORA Network Configuration File: /oracle/92/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.
NAMES.DIRECTORY_PATH= (ONAMES, TNSNAMES, HOSTNAME)
#Added by Robinson
tcp.validnode_checking = yes
tcp.excluded_nodes = (10.103.11.17)
tcp.invited_nodes = (10.103.11.17)