Use NTP to automatically and continuously set the time from Internet time servers.
You can set up one to three timeservers. Use those nearest to your geological location:
ucr set timeserver=de.pool.ntp.org timeserver2=asia.pool.ntp.org timeserver3=us.pool.ntp.org
invoke-rc.d ntp restart
Do this on all of your servers, or at least one and use this one as the NTP server for the others.