Saturday, January 20, 2018

networking - Local or public NTP servers?



For a relatively large network (thousands of hosts) - what are the arguments for and against running a locally managed (pool of) NTP server(s) (perhaps periodically set via some public NTP server) and having all other hosts on the network use that (pool of) NTP server(s) versus having all hosts simply use public NTP servers directly, say via ntp.pool.org?



Aside from the pros and cons, What is typical best practice today?


Answer



The best practice is to run your own pool of NTP servers set to sync from public NTP servers. In the event that your organization was to lose internet access, you would not want your clocks to become skewed. Further, it is rude to set thousands of hosts to public servers when you could (and should) operate a mirror.



Finally, if you have a secure computing requirement, then you should operate your own independent NTP hosts. You would require special hardware for these systems to operate.




EDIT: Since there was discussion of it, here is some hardware:



Any hardware supporting PPS seems to work on a modern ntpd. This includes some GPS units, although this seems to be rare, at least as rare as serial GPS units are these days. There are hardware devices sold explicitly for this function, however, including one product called TSync-PCIe. According to the manufacturer's site:




The TSync-PCIe offers several
configurations of a synchronized
timecode reader/generator package
offering flexibility and easy
integration of precise timing into an

embedded computing application. Choose
from synchronization to IRIG (and
other similar timecodes), GPS
(internal or external receivers), or
Precise Time Protocol
(PTP/IEEE-1588v2).
- Site Link: http://i564f.6o.to



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