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This is a copy for my reference, from this article. >> http://nlug.ml1.co.uk/2012/01/ntpq-p-output/831

There is more information in that link if you need more!

watch ntpq -p
Every 2.0s: ntpq -p                                                                                     Wed Oct 12 15:13:31 2016

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*ntp.venture3sys 198.60.22.240    2 u   38   64   35    0.515    4.729   2.850
+nu.binary.net   216.229.0.179    2 u   40   64   37   70.359   -5.134  17.058
-chl.la          132.163.4.102    2 u   40   64   37   88.081  -15.384  20.440
-repos.lax-noc.c 216.218.254.202  2 u   35   64   37   85.797  -16.423  19.348
+time-a.nist.gov .ACTS.           1 u   41   64   31   91.590   18.625  24.382
 LOCAL(0)        .LOCL.          10 l  305   64   20    0.000    0.000   0.000

Further detail:

Table headings:

  • remote – The remote peer or server being synced to. “LOCAL” is this local host (included in case there are no remote peers or servers available);
  • refid – Where or what the remote peer or server is itself synchronised to;
  • st – The remote peer or server Stratum
  • t – Type (u: unicast or manycast client, b: broadcast or multicast client, l: local reference clock, s: symmetric peer, A: manycast server, B: broadcast server, M: multicast server, see “Automatic Server Discovery“);
  • when – When last polled (seconds ago, “h” hours ago, or “d” days ago);
  • poll – Polling frequency: rfc5905 suggests this ranges in NTPv4 from 4 (16s) to 17 (36h) (log2 seconds), however observation suggests the actual displayed value is seconds for a much smaller range of 64 (26) to 1024 (210) seconds;
  • reach – An 8-bit left-shift shift register value recording polls (bit set = successful, bit reset = fail) displayed in octal;
  • delay – Round trip communication delay to the remote peer or server (milliseconds);
  • offset – Mean offset (phase) in the times reported between this local host and the remote peer or server (RMS, milliseconds);
  • jitter – Mean deviation (jitter) in the time reported for that remote peer or server (RMS of difference of multiple time samples, milliseconds);

Select Field tally code:

The first character displayed in the table (Select Field tally code) is a state flag (see Peer Status Word) that follows the sequence ” “, “x”, “-“, “#”, “+”, “*”, “o”:

  • ” ” – No state indicated for:
    • non-communicating remote machines,
    • “LOCAL” for this local host,
    • (unutilised) high stratum servers,
    • remote machines that are themselves using this host as their synchronisation reference;
  • x” – Out of tolerance, do not use (discarded by intersection algorithm);
  • ” – Out of tolerance, do not use (discarded by the cluster algorithm);
  • #” – Good remote peer or server but not utilised (not among the first six peers sorted by synchronization distance, ready as a backup source);
  • +” – Good and a preferred remote peer or server (included by the combine algorithm);
  • *” – The remote peer or server presently used as the primary reference;
  • o” – PPS peer (when the prefer peer is valid). The actual system synchronization is derived from a pulse-per-second (PPS) signal, either indirectly via the PPS reference clock driver or directly via kernel interface.

“refid”:

The refid can have the status values:

  • An IP address – The IP address of a remote peer or server;
  • .LOCL. – This local host (a place marker at the lowest stratum included in case there are no remote peers or servers available);
  • .PPS. – “Pulse Per Second” from a time standard;
  • .IRIG. – Inter-Range Instrumentation Group time code;
  • .ACTS. – American NIST time standard telephone modem;
  • .NIST. – American NIST time standard telephone modem;
  • .PTB. – German PTB time standard telephone modem;
  • .USNO. – American USNO time standard telephone modem;
  • .CHU. – CHU (HF, Ottawa, ON, Canada) time standard radio receiver;
  • .DCFa. – DCF77 (LF, Mainflingen, Germany) time standard radio receiver;
  • .HBG. – HBG (LF Prangins, Switzerland) time standard radio receiver;
  • .JJY. – JJY (LF Fukushima, Japan) time standard radio receiver;
  • .LORC. – LORAN-C station (MF) time standard radio receiver. Note, no longer operational (superseded by eLORAN);
  • .MSF. – MSF (LF, Anthorn, Great Britain) time standard radio receiver;
  • .TDF. – TDF (MF, Allouis, France) time standard radio receiver;
  • .WWV. – WWV (HF, Ft. Collins, CO, America) time standard radio receiver;
  • .WWVB. – WWVB (LF, Ft. Collins, CO, America) time standard radio receiver;
  • .WWVH. – WWVH (HF, Kauai, HI, America) time standard radio receiver;
  • .GOES. – American Geosynchronous Orbit Environment Satellite;
  • .GPS. – American GPS;
  • .GAL. – Galileo European GNSS;
  • .ACST. – manycast server;
  • .AUTH. – authentication error;
  • .AUTO. – Autokey sequence error;
  • .BCST. – broadcast server;
  • .CRYPT. – Autokey protocol error;
  • .DENY. – access denied by server;
  • .INIT. – association initialized;
  • .XFAC. – association changed (IP address changed or lost);
  • .MCST. – multicast server;
  • .RATE. – (polling) rate exceeded;
  • .TIME. – association timeout;
  • .STEP. – step time change, the offset is less than the panic threshold (1000ms) but greater than the step threshold (125ms).
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3 Comments

  1. Anonymous

    That site has been updated. At the very least, you might want to add PTP (Precision Time Protocol) to the list of refid sources. An indicator of what PTP meant was what brought me here. Thanks!

  2. Anonymous