[LINK] RFI: Clock Synchronisation in Hosts

Richard Archer rha at juggernaut.com.au
Wed Nov 12 12:49:48 AEDT 2014

On 12/11/14 12:21 PM, Roger Clarke wrote:
> My MacOSX 10.4.11 Date and Time tool has the 'Set date&  time automatically' option set, pointed at Apple Asia's server at time.asia.apple.com.
> I find it a serious concern that it doesn't work, and only synchs when I open the panel.

A description of problem and solution:


>  The defaults require several hours of constant access to the time
>  server in order to establish synchronization. If the initial sync
>  gets interrupted (by the computer going to sleep, for example), the
>  subsequent synchronization will not take place, causing the computer
>  to eventually drift from the correct time.

> Having my clock run fast by c. 5 seconds per day is one thing.  But there are a lot of host devices around the place which would create far bigger problems if they got significantly out of synch with authoritative time.
> What's the impression of Link Institute members about the frequency with which hosts in professionally-run organisations synch with time-servers?
> A related question would be:  what tolerance would be reasonable to expect from date-time stamps compared with an authoritative time-server, e.g.
>   +/- 1 second?
>   +/- 5 seconds?

I just checked my servers, and they are within a millisecond of correct 

My Mac and home Linux box are out by nearly 4 milliseconds, probably due 
to the jitter on my consumer-grade internet connection. But good enough 
for my requirements.


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