【Oracle问题集3】ORA-12543: TNS:destination host unreachable

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说明：【oracle问题集】是博主平时操作数据库遇到的问题以及解决方案。

执行语句：表示操作数据库过程
出错现象：表示操作数据库过程出现错误现象
出错原因：表示出现错误的原因
解决方法：表示解决错误的方法
相关知识：表示与这个主题相关的知识
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执行语句：
连接数据库：connect sys/oracle@192.168.135.243/orcl as sysdba
出错现象：
   ORA-12543: TNS:destination host unreachable
错误原因：

sqlnet.ora文件中的NAMES.DIRECTORY_PATH= (TNSNAMES,EZCONNECT)，添加ezconnect参数值，所以如果指定数据库实例，必须要跟上主机ip地址。请参考【Easy Connect Naming】。因此正确的写法是：CONNECTusername/password@host[:port][/service_name]
例如connect sys/oracle@192.168.135.243/orcl as sysdba

解决方法：

连接数据库时需要指定主机ip地址：connect sys/orcl@192.168.135.243/orcl as sysdba

相关知识：
      以下知识来源于oracle官方文档
Naming MethodDescriptionLocal Naming
Resolves anetservice namestored in atnsnames.orafile stored on a client
Local naming is most appropriate for simple distributed networks with a small number of services that change infrequently.
See Also:"Configuringthe Local Naming Method"
Directory Naming
Resolves a databaseservicename, net service name, ornet service aliasstoredin a centralized LDAP-compliant directory server
See Also:"Configuringthe Directory Naming Method"
Easy Connect Naming
Enables clients to connect to a database server without any configuration. Clients use a connect string for a simple TCP/IP address, consisting of a host name and optional port and service name:
CONNECTusername/password@host[:port][/service_name]
This method is recommended for simple TCP/IP environments.
See Also:"Usingthe Easy Connect Naming Method"
External Naming
Resolves service information stored in an a third-party naming service
See Also:"ConfiguringExternal Naming Methods"

相关监听配置测试工具命令：lnsrctl、tnsping


listener.ora文件内容：

# listener.ora Network Configuration File: /home/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER=
(SID_LIST=
  (SID_DESC=
  (SID_NAME=orcl)
  (ORACLE_HOME=/home/oracle/app/oracle/product/11.2.0/dbhome_1)
  )
)


LISTENER =
(DESCRIPTION_LIST =
  (DESCRIPTION =
   (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
   (ADDRESS = (PROTOCOL = TCP)(HOST=192.168.135.243)(PORT = 1521))
  )
)
ADR_BASE_LISTENER = /home/oracle/app/oracle

tnsnames.ora文件内容

# tnsnames.ora Network Configuration File: /home/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
ORCL =
(DESCRIPTION =
  (ADDRESS = (PROTOCOL = TCP)(HOST =192.168.135.243)(PORT = 1521))
  (CONNECT_DATA =
   (SERVER = DEDICATED)
   (SERVICE_NAME = orcl.192.168.132.243)
  )
)

sqlnet.ora

# sqlnet.ora Network Configuration File: /home/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.
NAMES.DIRECTORY_PATH= (TNSNAMES,EZCONNECT)
ADR_BASE = /home/oracle/app/oracle