[ntp:questions] Re: uk pool problem

Danny Mayer mayer at ntp.isc.org
Thu Aug 31 02:46:12 UTC 2006

Ronan Flood wrote:
> mayer at ntp.isc.org (Danny Mayer) wrote:
>> That's a separate issue. I was talking about a server giving you the
>> wrong answer. ntpdate will just accept it, while ntpd will compare it to
>> other answers it has received and drop it if it disagrees that much from
>> other answers it received.
> I wasn't referring to that; you must have missed the context of my
> comment, the quote from the website.

That's an issue for the pool operators. I did read the web site
reference. I don't understand how they determine who can register an NTP
pool server but if they accept addresses from anyone they have a major
problem if it is true that it shouldn't have been added to the pool.
Additionally there is evidence that the server sometimes gives a totally
incorrect answer but it's not clear to anyone why. There's no
information on the web site for the pool to indicate who owns or is the
contact for this server.

> Re accepting the wrong answer, ntpd would be as bad if you configured
> only one server.  ntpdate can be given multiple servers too, and will
> query them all and attempt some sanity checking.  I don't know if it's
> as good as ntpd, however, and I agree that using ntpd is the preferred
> approach.

I'd have to check the ntpdate code but I don't think it does anything
special to verify the receive data.


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