[ntp:questions] pruning the pool?

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Thu Jul 15 22:37:31 UTC 2010

Rob wrote:
> hymie! wrote:
>> My servers are configured to use
>> server 0.us.pool.ntp.org
>> server 1.us.pool.ntp.org
>> server 2.us.pool.ntp.org
>> server 3.us.pool.ntp.org
>> Through what I presume is a fluke of the DNS randomization, three of
>> my four hosts were:
>> .INIT. 16 u 390 512 0 0.000 0.000 4000.00
>> .INIT. 16 u 378 512 0 0.000 0.000 4000.00
>> .INIT. 16 u 384 512 0 0.000 0.000 4000.00
>> I tried searching the NTP web sites to figure out who
>>   maintains the NTP pools, and this was the best lead I got.
>>  If these hosts are no longer offerring NTP, can they
>>  (and perhaps others in that same net block) be removed
>>  from the pool?

Pool servers are babysat and removed automatically.

> Hosts that are not offering NTP are automatically removed from the pool.
> Unfortunately, with (commonly used versions of) ntpd this DNS lookup
> is only done when it is started.  So when you get 4 working NTP servers,
> it may well happen that they stop offering NTP service later and you get
> the above result.
> It can be fixed by restarting ntpd.

Isn't this greatly improved in NTP 4.2.7p22 and later?
 {When using the pool server option}

Aren't the pool servers tossed after 10 polls without
 surviving clock selection and then NTP will get IPs for
 more pool servers?


tos minclock 6 minsane 4 cohort 1

peer   myNTPserverClock.example.org iburst
server myNTPserverDyn.example.org iburst preempt
server myISPsNTPserver1.example.com iburst
server myISPsNTPserver2.example.com iburst
server myUpStreamsNTPserverA.example.net iburst
server myUpStreamsNTPserverB.example.net iburst

pool   0.us.pool.ntp.org iburst
pool   1.us.pool.ntp.org iburst
pool   2.us.pool.ntp.org iburst
pool   3.us.pool.ntp.org iburst

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