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Date:      Sun, 25 Oct 1998 13:23:06 +1030
From:      Greg Lehey <grog@lemis.com>
To:        Dan Nelson <dnelson@emsphone.com>, Brendan Kosowski <brendan@bmk.com.au>, FreeBSD Questions <freebsd-questions@FreeBSD.ORG>
Subject:   Re: Time calibration ?
Message-ID:  <19981025132306.F16609@freebie.lemis.com>
In-Reply-To: <19981024212131.A1534@emsphone.com>; from Dan Nelson on Sat, Oct 24, 1998 at 09:21:31PM -0500
References:  <Pine.BSF.3.96.981025115426.4700A-100000@garfield> <19981024201015.B29492@emsphone.com> <19981025124740.D16609@freebie.lemis.com> <19981024212131.A1534@emsphone.com>

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On Saturday, 24 October 1998 at 21:21:31 -0500, Dan Nelson wrote:
> In the last episode (Oct 25), Greg Lehey said:
>> On Saturday, 24 October 1998 at 20:10:15 -0500, Dan Nelson wrote:
>>> Your ISP seems to run one two hops away from you at
>>> Fddi0-0.lon7.Melbourne.telstra.net (139.130.239.228).
>>
>> Innteresting.  Where did you discover this server?  It's not in the
>> lists, and it turns out to be the most accessible for me as well.
>
> My standard procedure.  I traceroute the user, then ntptrace the last 3
> or 4 hops :)  Cisco servers have NTP client/server functionality built
> in, so many border routers can be used as NTP servers.  Lots of ISPs
> may also have an "official" server; I sometimes check to see if ntp.
> date. or mail.domain.com respond to NTP queries.

Thanks.  I've learnt something.  It also shows it's worth checking on
these things: first, there's a good chance that Telstra doesn't want
people to use this server (which is only stratum 3, and thus not in
the lists under http://www.eecis.udel.edu/~mills/ntp/servers.htm), and
secondly you're not necessarily buying anything by using it.  Until I
read your message, I was using terss.hba.marine.csiro.au, which is
stratum 1.  Here's the output of ntptrace for each server:

Fddi0-0.lon7.Melbourne.telstra.net:

$ ntptrace allegro
allegro.lemis.com: stratum 5, offset 0.011220, synch distance 0.44196
freebie.lemis.com: stratum 4, offset -0.004778, synch distance 0.42136
Fddi0-0.lon7.Melbourne.telstra.net: stratum 3, offset -0.008361, synch distance 0.02402
lon-core1.Melbourne.telstra.net: stratum 2, offset -0.006531, synch distance 0.02254
terss.hba.marine.csiro.au: stratum 1, offset -0.013036, synch distance 0.00549, refid 'GPS'

terss.hba.marine.csiro.au:

$ ntptrace allegro
allegro.lemis.com: stratum 3, offset -0.001456, synch distance 0.10211
freebie.lemis.com: stratum 2, offset -0.000076, synch distance 0.10406
terss.hba.marine.csiro.au: stratum 1, offset 0.019836, synch distance 0.00343, refid 'GPS'

In other words, although terss.hba.marine.csiro.au is further from
here than Fddi0-0.lon7.Melbourne.telstra.net, I get better time
synchronization.

Greg
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