The clocks of all the nodes in your cluster and the machine that runs the browser through which you access the Ambari Web interface must be able to synchronize with each other.
To check that the NTP service is on, run the following command on each host:
chkconfig --list ntpd
To set the NTP service to start on reboot, run the following command on each host:
chkconfig ntpd on
To turn on the NTP service, run the following command on each host:
service ntpd start
