[ntp:questions] Windows time question.

unruh unruh at wormhole.physics.ubc.ca
Fri Apr 22 21:09:54 UTC 2011

On 2011-04-22, E-Mail Sent to this address will be added to the BlackLists <Null at BlackList.Anitech-Systems.invalid> wrote:
> unruh wrote:
>> Richard B. Gilbert wrote:
>>> unruh wrote:
>>>> Rob wrote:
>>>>> Hal Murray wrote:
>>>>>>    pool<server-name>
>>>>>> will use as many addresses from server-name as it needs.
>>>>>> If it doesn't get enough with the first DNS lookup,
>>>>>>  it will try again in a minute or so, and keep trying
>>>>>>  until it gets enough.
>>>>>> The default is to collect 10 servers.
>>>>> If I were involved in the pool I would call that abuse!
>>>>> The pool DNS lookup now returns 3 servers, used to be 5.
>>>>> When everyone uses 10 servers the load on the pool as a
>>>>>  whole is twice what it would need to be, and 3 times
>>>>>  what would be the minimum reasonable value.
>>>>> Do the pool managers know that it works that way?
>> I do have a GPS PPS receiver. But that is not the question.
>>  The question is why ntpd would demand a default of 10 pool
>>   servers.
> It doesn't specifically.
>  It is up to maxclock of whatever sources that are designed
>   to spin up more.  IIRC manycast did this before pool was
>   modified to work more like manycast in that regard.
> On some of my NTP servers, I intentionally don't use
>  the pool command, rather I use a server *.pool.ntp.org
>  line, so that the server can pull manycasts up to maxclock,
>  without pulling more pool servers than the number in
>  server .conf lines.

The question still is why is maxclock so large by default?
>> The only reason I could think of is that the developers
>>  of ntpd do not trust the pool, and feel that they need
>>  that many to get a reasonable expectation of accurate
>>  time from the pool.
> I guess you didn't think of everything. (Shrug)

Undoubtedly I did not. Unfortunately you still have not given me any other
reason for this behaviour, or if you did, I do not understand it. 

> FYI, The pool command can also be used with sources other
>       than pool.ntp.org   e.g.
> pool clock.fmt.he.net iburst preempt            # Hurricane Electric Fremont, CA Pool he.net/adm/ntp.html
> pool clock.develooper.com iburst preempt        # develooper Pool support.ntp.org/bin/view/Servers/ClockDevelooperCom (you were already using them)
> pool time.bldrdoc.gov iburst preempt minpoll 10 # NIST Pool nist.gov/pml/div688/grp40/its.cfm

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