上周去给客户培训Oracle，讲到DG部分做实际配置演示的时候，碰到了ORA-28547故障，客户的数据库时11.2.0.1的版本，Window平台。
之前已经按照步骤把DG全部配置完成了，当准备在备库启用redo apply的时候，照例先检查一下两边远程归档路径是否有效：
select dest_name,status,error from v$archive_dest where dest_id<3;
此时备库的本地和远程归档路径状态都是VALID，但是主库就报一个：
ORA-28547：connection to server failed,probable Oracle Net admin error (DBD ERROR: OCISessionBegin)
由于和服务器连接失败，主库的归档无法通过LNS进程传递到备库，这和之前碰到的各种ORA-12541和ORA-12514的TNS连接错误还不太一样，因为用TNSPING命令去ping各自的NET SERVICE NAME都是正常的，并没有说找不到目标。
根据经验，当发生TNS或Oracle Net连接错误，首先就要去关注几个$ORACLE_HOME/network/admin下面的几个配置文件，通常是配置不正确造成的，以下是几个配置文件大致内容：
listener.ora
# listener.ora Network Configuration File: D:\oracle\product\11.2.0\dbhome_1\network\admin\listener.ora
# Generated by Oracle configuration tools.
#CLRExtProc
#DIRECT_HANDOFF_TTC_LISTENER = OFF
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = orcl)
(ORACLE_HOME = D:\oracle\product\11.2.0\dbhome_1)
(PROGRAM = extproc)
(ENVS = "EXTPROC_DLLS=ONLY:D:\oracle\product\11.2.0\dbhome_1\bin\oraclr11.dll")
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
)
)
ADR_BASE_LISTENER = D:\oracle
tnsnames.ora
# tnsnames.ora Network Configuration File: D:\oracle\product\11.2.0\dbhome_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
LISTENER_ORCL =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
ORACLR_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
)
(CONNECT_DATA =
(SID = CLRExtProc)
(PRESENTATION = RO)
)
)
orcl =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
)
)
sqlnet.ora
# sqlnet.ora Network Configuration File: D:\oracle\product\11.2.0\dbhome_1\network\admin\sqlnet.ora
# Generated by Oracle configuration tools.
# This file is actually generated by netca. But if customers choose to
# install "Software Only", this file wont exist and without the native
# authentication, they will not be able to connect to the database on NT.
SQLNET.AUTHENTICATION_SERVICES= (NTS)
NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)
网上google了几篇相关内容的文章，有的说要把sqlnet.ora中的SQLNET.AUTHENTICATION_SERVICES= (NTS)改为SQLNET.AUTHENTICATION_SERVICES= (NONE)，或者是把监听的HOST中改为IP地址，但都没有效果。而且前者会禁用操作系统验证，也就意味着必须用username/password@orcl的方式登录到服务器
最终通过查阅官方文档解决该问题，我们来看一下官方文档的描述：
应用于：
Oracle Net Services - Version 11.2.0.1 and later
Information in this document applies to any platform.
症状：