[ntp:questions] classic version 3 bug?

Tom Smith smith at cag.zko.hp.com
Wed Feb 27 17:47:39 UTC 2008

Tom Smith wrote:
> Edmund Lau wrote:
>> Hi All,
>> I seem to remember that ntp version 3 had a bug where if one of its 
>> servers was offline during initialization, ntpd would skip it and no 
>> longer poll the server even though the server comes back up later.  
>> Was this an actual bug?  Can someone point me to the docs (or bug 
>> report). Or was I dreaming this up?
>> Thanks
> I don't recall that to be the case. However, in version 3 OR 4,
> if you use a name for the server and the name can't be resolved to an 
> address
> during initialization, the behavior is as you describe. This can happen
> if the DNS server is inaccessible and the NTP server's name is not
> resolvable through the hosts file or some other means.
> -Tom

One clarification....

Version 4 is, I believe, different with regard to temporary DNS failures
in that it will retry those later. In the specific example above
(inacessible DNS server) version 4 might tolerate that whereas
version 3 would not. Both will knock the NTP serer off the list
if they get a permananent failure (NXDOMAIN) DNS response.


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