[ntp:questions] Leap second events

David J Taylor david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Sun Jan 1 08:56:38 UTC 2006

Similar to other reports, a had a mixed bag of results here due to some 
external servers correctly inserting the leap second and others not.  I 
have only external servers an no reference clock.

What I noticed was that the drift values stored in the ntp.drift files 
became very high (values near to 500), which were grossly incorrect. 
Under that situation, whilst ntp on two PCs recovered slowly towards 
normal (Bacchus and Stamsund), by 07:40 UTC the two other PCs had not, and 
were still showing the very high drift values.  Consequently I restarted 
ntp on those PCs at 07:40, deleting the ntp.drift files before the 

You can see the results here, although only offsets within +/- 100ms are 
recorded, so it's just the general disturbance which can be seen.  As I 
write, Hermes and Odin have just written more reasonable (although not 
correct) values into their drift files (been operating for about one 
hour), and appear to be gradually recovering, restarting when the offset 
exceeds 128ms but with a smaller offset drift rate each restart.


It seems to me that, where a single server is in error ntp copes nicely by 
ignoring it, but where many servers are in error, some sort of instability 
may result.

Happy New Year


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