RAC - NTP service failed

ERROR : 

"NTP common Time Server Check started...
PRVF-5410 : Check of common NTP Time Server failed
PRVF-5416 : Query of NTP daemon failed on all nodes
Result: Clock synchronization check using Network Time Protocol(NTP) failed

PRVF-9652 : Cluster Time Synchronization Services check failed


Solution : 

Besides the section that "Generated by Exadata",

/etc/ntp.conf  -- should have the following un-commented lines

restrict default ignore
restrict -6 default ignore
restrict 127.0.0.1
restrict -6 ::1
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10

-------------------------------------------------------------

# yum install ntp

# service ntpd stop
Shutting down ntpd:                                        [  OK  ]
# chkconfig ntpd off
# mv /etc/ntp.conf /etc/ntp.conf.org
# rm /var/run/ntpd.pid


If you wish to use NTP, you must add the "-x" option into the following line in the "/etc/sysconfig/ntpd" file.

OPTIONS="-x -u ntp:ntp -p /var/run/ntpd.pid"

# service ntpd restart