TNS-12542 TNS-12560 troubleshooting

Incorrect database listening status
$ Lsnrctl status

LSNRCTL for IBM/aix risc System/6000: Version 10.2.0.5.0-Production on 05-NOV-2012 08:54:08

Copyright (c) 1991,201 0, Oracle. All rights reserved.

Connecting to (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = test) (PORT = 1521 )))
TNS-12541: TNS: no listener
TNS-12560: TNS: protocol adapter error
TNS-00511: No listener
IBM/aix risc System/6000 Error: 79: Connection refused
Then, the following error is reported when you manually start the database:
$ Lsnrctl start

LSNRCTL for IBM/aix risc System/6000: Version 10.2.0.5.0-Production on 05-NOV-2012 08:54:12

Copyright (c) 1991,201 0, Oracle. All rights reserved.

Starting/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for IBM/aix risc System/6000: Version 10.2.0.5.0-Production
System parameter file is/oracle/product/10.2.0/db_1/network/admin/listener. ora
Log messages written to/oracle/product/10.2.0/db_1/network/log/listener. log
Error listening on: (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = test) (PORT = 1521 )))
TNS-12542: TNS: address already in use
TNS-12560: TNS: protocol adapter error
TNS-00512: Address already in use
IBM/aix risc System/6000 Error: 67: Address already in use

Listener failed to start. See the error message (s) abve...

/Oracle/product/10.2.0/db_1/network/trace/listener. trc

When the listener was not started, it was said that it was already running. Then I finally found the cause. Someone else encountered this problem on the internet, saying that there was a problem with the HOSTS file settings. Check the Host Name and hosts file of the local machine, sure enough, there is a problem. The two IP addresses point to the same host name. After deleting a host, start the listener. Everything is OK.

Modify with the root user:
# Cat/etc/hosts

# Internet Address Hostname # Comments
#192.9.200.1 net0sample # ethernet name/address
#128.100.0.1 token0sample # token ring name/address
#10.2.0.2 x25sample # x.25 name/address
#2000: 1: 1: 1: 209: 6bff: feee: 2b7f limit 6sample # ipv6 name/address
127.0.0.1 loopback localhost # loopback (lo0) name/address
192.168.101.189 test
192.168.101.190 test

Start the listener again:
$ Lsnrctl start

LSNRCTL for IBM/aix risc System/6000: Version 10.2.0.5.0-Production on 05-NOV-2012 08:58:47
Copyright (c) 1991,201 0, Oracle. All rights reserved.

Starting/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for IBM/aix risc System/6000: Version 10.2.0.5.0-Production
System parameter file is/oracle/product/10.2.0/db_1/network/admin/listener. ora
Log messages written to/oracle/product/10.2.0/db_1/network/log/listener. log
Listening on: (DESCRIPTION = (ADDRESS = (PROTOCOL = tcp) (HOST = test) (PORT = 1521 )))
Listening on: (DESCRIPTION = (ADDRESS = (PROTOCOL = ipc) (KEY = EXTPROC0 )))

Connecting to (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = test) (PORT = 1521 )))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for IBM/aix risc System/6000: Version 10.2.0.5.0-Production
Start Date 05-NOV-2012 08:58:49
Uptime 0 days 0 hr. 0 min. 0 sec
Trace Level off
Security ON: Local OS Authentication
SNMP ON
Listener Parameter File/oracle/product/10.2.0/db_1/network/admin/listener. ora
Listener Log File/oracle/product/10.2.0/db_1/network/log/listener. log
Listening Endpoints Summary...
(DESCRIPTION = (ADDRESS = (PROTOCOL = tcp) (HOST = test) (PORT = 1521 )))
(DESCRIPTION = (ADDRESS = (PROTOCOL = ipc) (KEY = EXTPROC0 )))
Services Summary...
Service "PLSExtProc" has 1 instance (s ).
Instance "PLSExtProc", status UNKNOWN, has 1 handler (s) for this service...
The command completed successfully

Summary: the setting of the/etc/hosts file is very important. The setting is incorrect and errors occur in many places, especially RAC. Many strange errors will be reported. pay more attention to the configuration.