[ntp:questions] pruning the pool?

Danny Mayer mayer at ntp.org
Sun Jul 18 23:00:53 UTC 2010


On 7/15/2010 6:37 PM, E-Mail Sent to this address will be added to the
BlackLists wrote:
> 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:
>>>  153.16.4.139 .INIT. 16 u 390 512 0 0.000 0.000 4000.00
>>>  153.16.4.133 .INIT. 16 u 378 512 0 0.000 0.000 4000.00
>>>  153.16.4.140 .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.
>  <http://www.pool.ntp.org/en/scores>
> 
>> 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?
> 

Not yet. That work is under way but it takes a lot of infrastructure
work to do that.

Danny

> e.g.
> 
> 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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