NTP: ntpq output explained

Host1:~# ntpq -p
remote refid st t when poll reach delay offset jitter
==========================================================
-navobs1.oar.net .USNO. 1 u 958 1024 377 89.425 -6.073 0.695
*navobs1.gatech. .GPS. 1 u 183 1024 375 82.102 1.639 0.281
-NAVOBS1.MIT.EDU .PSC. 1 u 895 1024 377 90.912 -0.207 0.368
+navobs1.wustl.e .GPS. 1 u 48 1024 377 76.890 1.093 0.525
-bigben.cac.wash .USNO. 1 u 924 1024 377 113.327 0.028 0.326
+tick.ucla.edu .GPS. 1 u 107 1024 377 102.470 2.032 0.482
-ntp.alaska.edu .GPS. 1 u 881 1024 377 168.741 5.180 5.157
-tock.mhpcc.hpc. .GPS. 1 u 933 1024 377 174.518 -1.094 0.054

Host2# ntpq -p
remote refid st t when poll reach delay offset disp
==========================================================
+128.252.19.1 .GPS. 1 u 495 1024 377 30.90 -6.366 8.26
*139.78.133.139 .USNO. 1 u 936 1024 377 48.43 -2.906 5.20

Columns Defined:
remote: peers speficified in the ntp.conf file
* = current time source
# = source selected, distance exceeds maximum value
o = source selected, Pulse Per Second (PPS) used
+ = source selected, included in final set
x = source false ticker
. = source selected from end of candidate list
– = source discarded by cluster algorithm
blank = source discarded high stratum, failed sanity

refid: remote source’s synchronization source

stratum: stratum level of the source

t: types available
l = local (such as a GPS, WWVB)
u = unicast (most common)
m = multicast
b = broadcast
– = netaddr

when: number of seconds passed since last response

poll: polling interval, in seconds, for source

reach: indicates success/failure to reach source, 377 all attempts successful

delay: indicates the roundtrip time, in milliseconds, to receive a reply

offset: indicates the time difference, in milliseconds, between the client server and source

disp/jitter: indicates the difference, in milliseconds, between two samples

Quick Update:
Here is a more in-depth reference:
https://pthree.org/2013/11/05/real-life-ntp/

3 thoughts on “NTP: ntpq output explained”

  1. ntpq -c rv output has changed in 4.2.6.

    I may be mistaken, but I think I have mapped the new output/values to the old style display.

    OLD NEW
    noise sys_jitter
    stability clk_wander
    jitter clk_jitter

    Please comment if this is incorrect.

  2. ntpq output: offset reached 0.000… now what?

    remote refid st t when poll reach delay offset jitter
    ======================================================
    +navobs1.wustl.e .GPS. 1 u 241 256 377 77.626 1.744 0.195
    -tick.ucla.edu .GPS. 1 u 136 256 377 102.069 2.019 2.281
    +ntp.alaska.edu .GPS. 1 u 207 256 377 168.971 0.528 6.612
    *GPS_NMEA(1) .GPS. 0 l 62 64 377 0.000 0.000 0.001
    LOCAL(0) .LOCL. 10 l 62 64 377 0.000 0.000 0.000
    Is it possible to get better resolution output from ntpq?

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