ORA-12545: Connect failed because target host or object does not exist

解决办法：

1、修改服务器端的配置文件listerner.ora，将host=IP修改为host=主机名

LISTENER_DSDB1 =
    (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = dsdb1-vip)(PORT = 1521)(IP = FIRST))
      (ADDRESS = (PROTOCOL = TCP)(HOST = dsdb1)(PORT = 1521)(IP = FIRST))

)
    )

2、重启监听

3、修改客户端的hosts文件，路径：C:\WINDOWS\system32\drivers\etc\hosts

在该文件中添加如下内容：

IP地址 dsdb1-vip
IP地址 dsdb2-vip
IP地址 dsdb1
IP地址 dsdb2

4、修改完成后，连接

SQL> conn hr/hr@dsmqis
Connected.
SQL> conn hr/hr@dsmqis
Connected.
SQL> conn hr/hr@dsmqis
Connected.
SQL> conn hr/hr@dsmqis
Connected.
SQL> conn hr/hr@dsmqis
Connected.
SQL> conn hr/hr@dsmqis
Connected.
SQL> conn hr/hr@dsmqis
Connected.