一朋友启动监听lsnrctl start 发现报错TNS-12547  TNS-12560 TNS-00517
[oracle@zyx ~]$ lsnrctl start
LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 25-APR-2016 06:14:23
Copyright (c) 1991, 2013, Oracle.  All rights reserved.
Starting /u01/app/oracle/product/11.2/db_1/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 11.2.0.4.0 - Production
System parameter file is /u01/app/oracle/product/11.2/db_1/network/admin/listener.ora
Log messages written to /u01/app/oracle/diag/tnslsnr/ogg1/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=zyx)(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=zyx)(PORT=1521)))
TNS-12547: TNS:lost contact
 TNS-12560: TNS:protocol adapter error
  TNS-00517: Lost contact
   Linux Error: 104: Connection reset by peer
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
TNS-12541: TNS:no listener
 TNS-12560: TNS:protocol adapter error
  TNS-00511: No listener
   Linux Error: 111: Connection refused

试过重建监听、创建静态监听都不行........

后来在网上看到一篇这样的文章，然后就搞定咯...
http://www.linuxidc.com/Linux/2014-05/101152.htm

解决办法：查看/etc/hosts 文件内容
[root@zyx ~]# cat /etc/hosts
127.0.0.1    localhost.localdomain localhost4 localhost4.localdomain4
::1        localhost.localdomain localhost6 localhost6.localdomain6
192.168.11.111     zyx

将127.0.0.1 后面添加localhost
[root@zyx ~]# cat /etc/hosts
127.0.0.1      localhost localhost.localdomain localhost4 localhost4.localdomain4
::1           localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.11.111        zyx