1.local listener is set by the oraagent which is started by crsd.(it will automatically set the local_listener value thorugh alter system command if it is not set in the spfile)2.the log file for the ora agent will be in this below locationGRID_HOME/log/nodename}/agent/crsd/oraagent_oracle/oraagent_oracle.log - This is the important log file practically useful3.the lsnrctl status will start the IPC endpoints mentioned in the endpoint_listener.ora4.The remaining listeners are started by the oraagent based on the tnsnames.ora configuration5.through starting the listeners..the pmon registers its instance/services with the listeners.6.even if we remove the listener.ora...if we start the local listener through srvctl command it will create the listener.ora file.

ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER_SCAN1=ON # line added by Agent - This line will be added in the listener.ora if we start the local listener with the help of the srvctl command

7.the use of the scan listener is that we dont need to specify the changes in the hostname in the endpoint_listener.ora file in the client side.

8.scan listener will take care of the connection to the local listener with the client.

9.scan listener will provide the connection detail of a listener which is less loaded.

10.the oraagent makes the TCP port alive on all the listener file end point hosts.

11.if we dont set the local_listener value automatically db will set its value.

12.we must set the local_listener and remote_listener value same as the scan_listener.

13.