Clock Synchronization here in the "Digital ToyBox"

The time-of-day clock in each of the computers inside the firewall (including the webcams) is synchronized with that of the firewall computer itself.  The firewall clock is, in turn, synchronized with any one of several external NTP (Network Time Protocol) servers at any given moment.

Why did I go to all this trouble? ... well, for the fun of it really.   My father was a watchmaker, and I am fortunate to have inherited from him a curiosity for how things work ... things like timekeeping devices.  I am still fascinated by a well-made chronometer mechanism like my faithful old Rolex or the Jaeger-leCoultre wrist alarm chronometer I inherited from my father.   So, getting my computers to reflect accurate time is just an extension of this curiosity.

And besides, I'm tired of tweaking the system clock every time I rebuild one of the computers.   :-)

The time is usually accurate within 100 milliseconds (0.1 second) of the real world, unless the systems have lost sync for some reason ... usually a network problem.  If sync is lost, the clocks keep running independently until a lock is regained, at which time any required adjustments are made.

The firewall computer is a client of what are known as Public Stratum-2 NTP Servers.  Therefore the firewall clock becomes stratum-3, and the computers behind the firewall, including this web server, operate at stratum-4.  All of this means that there are three "layers" of clocks between bluenose and the current reference clock at stratum-0.

If you reload this page a few times you will notice that the clock offset is constantly being corrected.  It doesn't happen often, but you may catch a change in the name of the stratum-2 reference clock as the firewall continuously tracks three widely dispersed public NTP servers:    NRC-Canada  |  Canadian Meteorological Centre  |  University of Regina  . . . .

So, for you terminally curious trivia fans, 'ntptrace' reports ...

	Current bluenose approximate clock offset is:	-0.000001 second
	. . . with respect to the stratum-0 reference:	'PPS'
	Current location of the stratum-2 clock is:	National Research Council of Canada
	UTC date/time this trace was completed:	2012/02/04, 05:48:29 UTC

Question marks indicate a temporary loss of syncronization traceback information ... try again. ACTS = NIST Automated Computer Time Service ATOM = Atomic Clock GPS = Global Positioning System Satellites PPS = Master clock synchronised with multiple Atomic Clocks. USNO = United States Naval Observatory WWV-WWVB-WWVH = NIST Time-standard Broadcast

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If you would like to know more about NTP time servers and about software for Windows/UNIX/Linux/BSD/Java/etc.,  visit the ntp.org  web site.