[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 

>  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
>  + <> 3 u 26 64 377 1.039
>  3.905 15.877
>  titan.cais.rnp. <> 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> <> 3
>  u 32 64 377 150.767 -1.882 25.244
>  LOCAL(0) <> 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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