Time synchronization

Time synchronization on the CTIO computers is done as follows:

1. An automatic job is invoked on Cerro Tololo machine ctioa7 at 0045h, 0445h, 0845h, 1245h, 1645h, 2045h.
   
    
2. This job runs the 'ntpdate' program which uses the ntp protocol to acquire precise time and other information from each of the following sites:
   
   *norad.arc.nasa.gov
   
   *tick.usno.navy.mil
   
   *tock.usno.navy.mil
   
   *ntp1.sura.net
   
   *ntp2.sura.net
   
   *louie.udel.edu
   
   *ntp.css.gov
   
    
3. The ntpdate program uses the data provided by the above machines and applies some sophisticated corrections to the data to compensate for packet transmission time, and sets the time on ctioa7 accordingly.
   
    
4. All other SunOS, Solaris, and Linux computers run an automatic job once an hour on the hour.
   
    
5. This job is 'rdate' which synchronizes their time w/ ctioa7 (for machines on Cerro Tololo) or w/ ctios5 (for machines in La Serena).
   
   
   
   Here is the crontab entry as it appears on ctioa7:
   
   
   
   45 0,4,8,12,16,20 * * * /usr/etc/ntpdate -s -p 8 norad.arc.nasa.gov \ tick.usno.navy.mil tock.usno.navy.mil ntp1.sura.net ntp2.sura.net \ louie.udel.edu ntp.css.govra7(42)
   
   
   
   Here is the typical SunOS crontab entry on Cerro Tololo:
   
   
   
   0 * * * * /bin/touch /dev/console;/usr/ucb/rdate ctioa7 \ 1> /dev/null 2> /dev/null

Jim Hughes (jhughesATnoao.edu)