[ntp:questions] Re: asyncronous path between "time client" and ntp server
Brad Knowles
brad at stop.mail-abuse.org
Mon Oct 10 22:05:53 UTC 2005
At 3:37 PM -0400 2005-10-10, Bob Beers wrote:
> I will change to br.ntp.pool.org <http://br.ntp.pool.org>, but how do I
> specify 4 unique
> servers in br.pool? 0., 1., and 2. seem to work, but 3. does not resolve.
> How would I specify all (6) br servers?
There is no 3. for any of the pool.ntp.org zones. The
pool.ntp.org zones are intended to help fill out gaps in your list of
explicit servers, and to provide a "good enough" server to anyone who
doesn't have anything better. In the latter case, servers in
us.pool.ntp.org should be "good enough" for anyone anywhere in the
world, if they should happen to have their system configured that way.
Start with your ISP. They probably have time servers you can
use. If not, they probably know of some good time servers nearby.
After that, go to the list of servers at
<http://ntp.isc.org/bin/view/Servers/StratumTwoTimeServers>, and look
for those located in your country. After that, if you still need
some more servers, go to pool.ntp.org -- the numbered sub-zones of
us.pool.ntp.org should be more than enough to help fill out the list.
In other words, follow the logic at
<http://ntp.isc.org/bin/view/Support/SelectingOffsiteNTPServers>.
> server 0.br.pool.ntp.org <http://0.br.pool.ntp.org> iburst
> restrict 0.br.pool.ntp.org <http://0.br.pool.ntp.org> nomodify notrap nopeer
The "restrict" keyword only works with IP addresses, not
hostnames. See
<http://ntp.isc.org/bin/view/Support/TroubleshootingNTP>, especially
section 9.4.
> h:/tmp# ntpq -p
> remote refid st t when poll reach delay offset jitter
>
>==============================================================================
> +200.141.215.162 200.19.74.21 <http://200.19.74.21> 3 u 26 64 377 1.039
> 3.905 15.877
> titan.cais.rnp. 104.101.79.255 <http://104.101.79.255> 2 u 106 1024 77
> 534.701 -273.25 42.700
> ima.cipsga.org <http://ima.cipsga.org>. .STEP. 16 u - 1024 0 0.000 0.000
> 4000.00
> *time.uswo.net <http://time.uswo.net> 130.126.24.44 <http://130.126.24.44> 3
> u 32 64 377 150.767 -1.882 25.244
> LOCAL(0) 73.78.73.84 <http://73.78.73.84> 5 l 50 64 377 0.000 0.000 0.001
You've got only two sane servers that you're talking to. That's
bad. Moreover, you're using the "local clock" as one of your
servers, which you definitely should not be doing unless you really
understand what it does and why.
Follow the advice above.
--
Brad Knowles, <brad at stop.mail-abuse.org>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
SAGE member since 1995. See <http://www.sage.org/> for more info.
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