Ask about Listener in Oracle RAC 11gR2

Hi all,

   My DB version 11gR2 64 on RHEL 5.8. And it's RAC DB two nodes.

   I used DNS to configure SCAN IPs (it includes 3 IPs). DNS entry name : rac-scan.test.com

   I used LSNRCTL STATUS to view listener information, and it look like:

   LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 28-MAR-2013 04:28:51

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Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.3.0 - Production
Start Date                12-MAR-2013 15:24:59
Uptime                    15 days 13 hr. 3 min. 53 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      ON
Listener Parameter File   /u01/app/grid/11.2.0.3/network/admin/listener.ora