[ntp:questions] Re: ntpq -np

Ronan Flood ronan at noc.ulcc.ac.uk
Mon Mar 21 16:30:39 UTC 2005


Charles <charles97 at dunjas.com> wrote:

> When the ntpq -np command is issued, the second column is labeled REFID.
> 
> The number in the second column are always different from the numbers
> in the first column. I do not unstand the significance of the REFID
> numbers.
> I recognize that they are IP numbers, but what is the relationship?

The second column is the time-source to which the server in the first
column is synchronised.  It can be another NTP server, or a reference
clock.  Eg

 128.86.8.123    .MSF.            1 u  879 1024  377    4.607   -0.418   0.527
 128.86.16.123   128.86.8.123     2 u  348 1024  377    1.538   -1.976   0.252

128.86.8.123 is synchronised to an MSF radio clock, 128.86.16.123 is
synchronised to 128.86.8.123.

> The term "reference clock" appears frequently in this newsgroup. It
> appears that is used to talk about the one clock with an asterisk
> beside it. Is that correct?

No, a reference clock is a hardware time source such as a GPS receiver,
MSF/DCF/WWV(B) receiver, high-precision pulse-per-second generator, etc.
Stratum-1 NTP servers are connected to reference clocks, and will usually
be synchronised to them, hence reference clocks generally show up with
'*' next to them in the ntpq -p display.

-- 
                      Ronan Flood <R.Flood at noc.ulcc.ac.uk>
                        working for but not speaking for
             Network Services, University of London Computer Centre
     (which means: don't bother ULCC if I've said something you don't like)



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