[oracle@rac01 admin]$ lsnrctl status

LSNRCTL for Linux: Version 10.2.0.1.0 – Production on 11-FEB-2014 15:32:40

Copyright (c) 1991, 2005, Oracle.  All rights reserved.

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))

TNS-12541: TNS:no listener

TNS-12560: TNS:protocol adapter error

TNS-00511: No listener

Linux Error: 111: Connection refused

Solution.

Modified the /etc/hosts file.
Back to your old ways.
127.0.0.1 localhost. localdomain localhost
Re-establishing listening.
can immediately (do sth)