What is the listener?

*Listener .ora file contains server-side network configuration parameter

*The Physical location of that  file is "$ORACLE_HOME/newtwork/admin/"

Default Listener.ora contains

<listener_name> =
 (DESCRIPTION_LIST =
  (DESCRIPTION =
   (ADDRESS_LIST =
    (ADDRESS = (PROTOCOL = TCP)(HOST = <db_hostname>)(PORT = <port_name>))
   )
  )
 )

SID_LIST_<listener_name> =
 (SID_LIST =
  (SID_DESC =
   (SID_NAME = <DB_sid>)
    (ORACLE_HOME = <Oracle_home Location>)
  )
 )

in above we have to replace host into machine "IP Address" and SID_Name is Instance name

LISTENER =
 (DESCRIPTION_LIST =
  (DESCRIPTION =
   (ADDRESS_LIST =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.171)(PORT = 1521))
   )
  )
 )

SID_LIST_LISTENER =
 (SID_LIST =
  (SID_DESC =
   (SID_NAME = proddb)
    (ORACLE_HOME = /u01/app/oracle/product/11.2.0/dbhome_1)
  )
 )

Once we did the configuration we should start the listener again

i)To  start listener

oracle@oracle11g~]$ lsnrctl start

II)To stop listener

oracle@oracle11g~]$ lsnrctl stop

III)To view status

oracle@oracle11g~]$ lsnrctl status

eitherway ,we can use the lsnrctl utility at os level

oracle@oracle11g~]$ lsnrctl

 Start listener from that utility

LSNRCTL> start

 Stop listener

LSNRCTL> stop

 Status of the listener

LSNRCTL> status

Check listener at os level

At OS level, you can check background process tns

# ps –ef|grep tns