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I'm trying to get actual NTP drift on Macs connected to a local NTP server.

  • When reading /var/db/ntp.drift file I get -37.521 which according to PPM to milliseconds conversion gives -3241ms of drift.

  • When using ntpq -c lpeer I get something like this:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*172-1-1-5.light 164.67.62.212    2 u   57   64  377  199.438   38.322  29.012

which gives me offset of 38.322ms

  • Finally, sntp 172.1.1.5 outpus this:
2016 Jan 21 18:41:45.248591 +0.019244 +/- 0.022507 secs

which says having about 19ms of drift.

I'm confused which one the approaches gives accurate NTP drift?

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sntp gives the current offset. The ntp.drift file is updated only occasionally, I think when the daemon starts.

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