No listener.ora file is required for LISTENER to operate. Try to move, rename, remove, or delete listener.ora file & then restart the listener.
Every Oracle DB tries once every 60 seconds to register itself with LISTENER as shown below:
tail -f /u01/app/oracle/product/11.2.0/xe/log/diag/tnslsnr/XXXXX/listener/alert/log.xml <msg time='2012-10-25T01:15:50.522-07:00' org_id='oracle' comp_id='tnslsnr' type='UNKNOWN' level='16' host_id='host.domain' host_addr='XX.XX.XX.XX'> <txt>25-OCT-2012 01:15:50 * service_update * XE * 0 </txt> </msg> |