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14.7. NTP Toolkit
There are a number of utilities available to check if
NTP is doing it's job. The
ntpq -p command
will print out your system's current time status.
# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*cudns.cit.corne ntp0.usno.navy. 2 u 832 1024 377 43.208 0.361 2.646
LOCAL(0) LOCAL(0) 10 l 13 64 377 0.000 0.000 0.008
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The
ntpdc -c loopinfo will display
how far off the system time is in seconds, based upon the last time
the remote server was contacted.
# ntpdc -c loopinfo
offset: -0.004479 s
frequency: 133.625 ppm
poll adjust: 30
watchdog timer: 404 s
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ntpdc -c kerninfo will display
the current remaining correction.
# ntpdc -c kerninfo
pll offset: -0.003917 s
pll frequency: 133.625 ppm
maximum error: 0.391414 s
estimated error: 0.003676 s
status: 0001 pll
pll time constant: 6
precision: 1e-06 s
frequency tolerance: 512 ppm
pps frequency: 0.000 ppm
pps stability: 512.000 ppm
pps jitter: 0.0002 s
calibration interval: 4 s
calibration cycles: 0
jitter exceeded: 0
stability exceeded: 0
calibration errors: 0
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A slightly more different version of
ntpdc -c kerninfo is
ntptime
# ntptime
ntp_gettime() returns code 0 (OK)
time c35e2cc7.879ba000 Thu, Nov 13 2003 11:16:07.529, (.529718),
maximum error 425206 us, estimated error 3676 us
ntp_adjtime() returns code 0 (OK)
modes 0x0 (),
offset -3854.000 us, frequency 133.625 ppm, interval 4 s,
maximum error 425206 us, estimated error 3676 us,
status 0x1 (PLL),
time constant 6, precision 1.000 us, tolerance 512 ppm,
pps frequency 0.000 ppm, stability 512.000 ppm, jitter 200.000 us,
intervals 0, jitter exceeded 0, stability exceeded 0, errors 0.
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Yet another way to see how well NTP is working is
with the
ntpdate -d command. This will
contact an NTP server and determine the time difference
but not change your system's time.
# ntpdate -d 132.236.56.250
13 Nov 14:43:17 ntpdate[29631]: ntpdate 4.1.1c-rc1@1.836 Thu Feb 13 12:17:20 EST 2003 (1)
transmit(132.236.56.250)
receive(132.236.56.250)
transmit(132.236.56.250)
receive(132.236.56.250)
transmit(132.236.56.250)
receive(132.236.56.250)
transmit(132.236.56.250)
receive(132.236.56.250)
transmit(132.236.56.250)
server 132.236.56.250, port 123
stratum 2, precision -17, leap 00, trust 000
refid [192.5.41.209], delay 0.06372, dispersion 0.00044
transmitted 4, in filter 4
reference time: c35e5998.4a46cfc8 Thu, Nov 13 2003 14:27:20.290
originate timestamp: c35e5d55.d69a6f82 Thu, Nov 13 2003 14:43:17.838
transmit timestamp: c35e5d55.d16fc9bc Thu, Nov 13 2003 14:43:17.818
filter delay: 0.06522 0.06372 0.06442 0.06442
0.00000 0.00000 0.00000 0.00000
filter offset: 0.000036 0.001020 0.000527 0.000684
0.000000 0.000000 0.000000 0.000000
delay 0.06372, dispersion 0.00044
offset 0.001020
13 Nov 14:43:17 ntpdate[29631]: adjust time server 132.236.56.250 offset 0.001020 sec
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If you want actually watch the system
synchronize you can use
ntptrace.
# ntptrace 132.236.56.250
cudns.cit.cornell.edu: stratum 2, offset -0.003278, synch distance 0.02779
truetime.ntp.com: stratum 1, offset -0.014363, synch distance 0.00000, refid 'ACTS'
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If you need your system time synchronized immediately
you can use the
ntpdate remote-servername
to force a synchronization. No waiting!
# ntpdate 132.236.56.250
13 Nov 14:56:28 ntpdate[29676]: adjust time server 132.236.56.250 offset -0.003151 sec
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