[ntp:questions] Re: Public servers?

David L. Mills mills at udel.edu
Thu Jul 31 15:06:32 UTC 2003


I don't understand what you mean by "if somebody don't want to sync to 
Windows machine?" In and of itself, that is not a useful quality 
discriminator. The mitigation and grooming algorithms in ntpd are a 
wonderful quality discriminator and pool.ntp.org is a completely correct 
way to discover a swatch of servers from which ntpd can pick.

The public lists have been around for twenty years in one form or 
another. I originally intended the lists for use by campus and workplace 
network administrators, as in the early days before PCs. They are still 
very useful when designing secondary and tertiary NTP subnets, but less 
so for j-random PC users. There is no way to make everybody happy about 
the lists and I won't even try.

I don't apologize for the liveness or deadness of the public lists, not 
even a little. What you see is exactly what I get and I do not volunteer 
to groom the lists in any way. Many times in the past some well meaning 
folkster has pointed out absent response from one server or another only 
  to discover the DNS has changed or the server has been temporarily 
disabled. I insist on solid evidence, such as notification from the 
designated responsible person or confirmed report the server 
organization has filed for bankruptcy. The latter happens a lot.

There are scripts around that swallow the lists and independently verify 
the entries. The issue is whether the swallower can effectively convey 
the access policy for automatic retrieval. We have discussed this issue 
many times in the NTP developers corps and have considered various ways 
to codify the access rules, but this gets awkward when it comes to 
geographic scope. My advice is don't use the lists for j-random PCs. 
Better to pester your ISP.


The lists change almost on a daily basis. There has been a lot of evil 
in my past experience when some j-random boob caches the lists and I get 
flak from folks (like you) who complain the lists are out of date. The 
mea culpa middle finger points at multiple target cachers. Once you 
parse the lists and verify entries and select candidates, update your 
configuration file and lobotomize all memory of past actions. Do NOT, as 
some silicon boobs do now, do a DNS lookup for every NTP packet sent.


Piotr Trojanek wrote:

> In article <bg8pim$g9l$1 at dewey.udel.edu>, David L. Mills wrote:
>>If your script has discovered primary and secondary servers appearing in 
>>the public lists without respecting the access controls, you have done 
>>an evil, evil thing.
> Yes, my fault. The reason was that I had experiences with stratum 1/2 list
> when trying to find server that I could sync to and finding inactive or
> out of sync ones.
> Once discovered all data is provided from local database, so no more
> overhead is putted on servers.  Mayby some kind of more "up to date"
> list than official staratum 1/2 would prevent people from such a ideas
> like mine? As stated in pool.ntp.org it provides no way to check quality
> of server we get in DNS round robin -- ie. if somebody don't want to 
> sync to Windows machine?
> But there really seems to be no way to make everybody happy about
> NTP server lists...:(

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