[ntp:questions] time delta between clients

Danny Mayer mayer at ntp.isc.org
Fri Dec 21 04:10:04 UTC 2007


Per Hedeland wrote:
> In article <4761F0AA.3060003 at cag.zko.hp.com> Tom Smith
> <smith at cag.zko.hp.com> writes:
>> Rick Jones wrote:
>>> Rick Jones <rick.jones2 at hp.com> wrote:
>>>> Here is what I have now that I've dropped the minpoll from the server
>>>> and dropped LOCAL:
>>>> peer bl480c2 minpoll 3 maxpoll 4 iburst
>>>> server 10.208.0.1 iburst
>>>> server 10.0.0.1
>>>> server 10.202.1.1
>>> Scratch that - I commented-out the last two servers.
>>>
>>> rick jones
>> I think you may have problems, even in the mythical zero-latency network,
>> getting the skew consistently below double the clock tick of the system
>> with the largest clock tick interval.
> 
> Hm, if you were a newbie here, I'd assume that you simply don't know
> what you're talking about, but since you aren't, I must be
> misunderstanding you as you appear to be saying that two Unix hosts with
> the traditional 100 Hz clock (on the same LAN) couldn't achieve a skew
> consistently below 20 ms - while (at least) sub-millisecond offsets in
> such setups are commonplace and discussed here every other day.
> Apparently not even Windows has the kind of problem you suggest anymore.
> 

While Rick may be a relative newbie to NTP he has had years of
conducting performance analysis of applications and systems. His
performance testing of BIND9 is probably *the* seminal reference on DNS
testing.

Danny



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