On 12-Nov-14 12:21 PM, Roger Clarke wrote: > What's the impression of Link Institute members about the frequency with > which hosts in professionally-run organisations synch with time-servers?
If by "hosts in professionally-run organisations" you mean those with data centres, they have their own clock time source (GPS synched or atomic clock). This is known as a Stratum level 0. This would be connected to an NTP server which provides a Stratum level 1 capability for the rest of the data centre. Each time there s an extra hop, the level number goes up. Stratum 2, 3 etc. Synchronisation is done on a sort of continuous basis. I say sort of because it's part of a feedback loop. The clock to be synchronised checks its internal time against the reference and doesn't just reset to correct time, it adjusts itself to run more accurately. At the Stratum 1-2 levels tolerances are in the tens of millisecond ranges. If you need time stamps, that's what you need. No self respecting data centre would use an external source. See here for more gory details http://en.wikipedia.org/wiki/Network_Time_Protocol -- Regards brd Bernard Robertson-Dunn Sydney Australia email: [email protected] web: www.drbrd.com web: www.problemsfirst.com Blog: www.problemsfirst.com/blog _______________________________________________ Link mailing list [email protected] http://mailman.anu.edu.au/mailman/listinfo/link
