[ntp:questions] Windows time question.

unruh unruh at wormhole.physics.ubc.ca
Fri Apr 22 17:05:41 UTC 2011

On 2011-04-22, Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
> On 4/22/2011 11:22 AM, unruh wrote:
>> On 2011-04-22, Rob<nomail at example.com>  wrote:
>>> Hal Murray<hal-usenet at ip-64-139-1-69.sjc.megapath.net>  wrote:
>>>>> I would have hoped that the pool folk kept their documentation up-to-date,
>>>>> so I'll post that on their list.  You didn't mention how to control the
>>>>> number of servers uses - is it just multiple "pool" entries?
>>>> You only need one pool command.
>>>>    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.
>> I agree. It is absurd. It seems to indicate that the ntp folk really
>> really do not trust the pool, and figure that if you get fewer than 10, you have a
>> reasonable chance that a majority will deliver bad time. Ie, they appear
>> to feel that the pool is a pretty useless souce of time.
>>> Do the pool managers know that it works that way?
> Anyone who doubts the accuracy, legitimacy, etc. of pool services should 
> be able to purchase a GPS timing receiver and get the time from "the 
> horse's mouth".  The investment required is about $100 US at a minimum. 
> Or, just about every country in the world has its "National Bureau of 
> Standards" equivalent and many broadcast a time signal; e.g. WWV, WWVA, 
> WWVB, WWVH, JJY, CHU(?), etc.

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. 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. 

> If you're really paranoid, you can spend a small fortune and get an 
> "atomic clock" of your very own!  The NBS will cheerfully calibrate it 
> for you!

GPS PPS is fine for me, thank you, but then my timekeeping wants/needs
are not the question being addressed. What is being addressed is whether
or not the developers of ntpd "doubts the accuracy, legitimacy, etc. of
pool services" 


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