[ntp:questions] Re: NTP "maximum error" on local network

Thu, 18 May 2006 11:15:11 -0700 

[EMAIL PROTECTED] wrote:


------------------ client 1 -----
# ntpq -pcrv
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
*192.168.2.2     .NIST.           1 u    8   16  377    0.316   -0.004
 0.049
assID=0 status=0644 leap_none, sync_ntp, 4 events,
event_peer/strat_chg,
version="ntpd [EMAIL PROTECTED]:4.2.0a+stable-8-r Fri Sep  9 16:44:48 UTC 2005
(1)"?,
processor="i686", system="Linux/2.6.14-ck1", leap=00, stratum=2,
precision=-18, rootdelay=0.311, rootdispersion=23.428, peer=30804,
refid=192.168.2.2,
reftime=c8170ae1.7219220f  Thu, May 18 2006 11:01:53.445, poll=4,
clock=0xc8170b1d.39cd0bb6, state=4, offset=-0.008, frequency=212.134,
noise=0.006, jitter=0.214, stability=0.176

----------- client 2 --------------

# ntpq -pcrv
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
*192.168.2.2     .NIST.           1 u    -   16  377    0.327   -0.010
 0.103
assID=0 status=06b4 leap_none, sync_ntp, 11 events,
event_peer/strat_chg,
version="ntpd [EMAIL PROTECTED]:4.2.0a+stable-8-r Fri Sep  9 16:44:48 UTC 2005
(1)"?,
processor="i686", system="Linux/2.6.14-ck1", leap=00, stratum=2,
precision=-18, rootdelay=0.327, rootdispersion=22.889, peer=7436,
refid=192.168.2.2,
reftime=c8170e61.c989df11  Thu, May 18 2006 11:16:49.787, poll=4,
clock=0xc8170e75.fd7a13c2, state=4, offset=-0.010, frequency=183.551,
noise=0.005, jitter=0.103, stability=0.165

-------- server --------------

# ntpq -pcrv
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
*LOCAL(1)        .NIST.           0 l   18   64  377    0.000    0.000
 0.004
assID=0 status=0544 leap_none, sync_local_proto, 4 events,
event_peer/strat_chg,
version="ntpd [EMAIL PROTECTED] Fri Sep 23 21:02:05 EDT 2005 (1)"?,
processor="i686", system="Linux/2.6.16.14", leap=00, stratum=1,
precision=-18, rootdelay=0.000, rootdispersion=12.198, peer=11860,
refid=NIST, reftime=c8170f79.d6b87379  Thu, May 18 2006 11:21:29.838,
poll=10, clock=0xc8170f8b.90c7b02d, state=4, offset=0.000,
frequency=0.000, noise=0.000, jitter=0.004, stability=0.000

-------------------------------------------------------------

I am trying to build an isolated system, disconnected from the rest of
the internet, so I set the REFID to "NIST" and stratum to 0. If this is
a stupid thing to do, please let me know :)
I wouldn't go so far as to call in "stupid" but it is not correct and it is not necessary. (But don't ask what I would have said 25 or 30 years ago!) If you don't specify the refid, I believe it defaults to ".LCL.", ".LOCL." or something similar. That simply says that the reference is your local clock. .NIST. is not correct because it implies that the time comes from the National Institute of Standards and Technology when, in fact, it does not.
Even if your local clock was originally set to a time taken from NIST, there is a 99.99999999% probability that the time has since deviated from the correct value. It is not unusual for a local clock to drift as much as four seconds per day. Some local clocks are much worse than that. 

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