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On Sat, 24 Dec 2005 19:33:26 -0500 |
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Philip Webb <purslow@×××××××××.ca> wrote: |
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> There will be a leap second between 051231 235959 & 060101 000000 . |
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> Does anyone know how the time servers used by NTP handle this ? |
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> Is it just left to the local machine to realise it's 1 sec fast |
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> & adjust over a few hours or does something else alert it to correct |
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> things ? If the former, it could create problems for those running |
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> experiments; if the latter, does anyone know how it is done ? |
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> The last leap second was 1998/9 , |
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According to the RFC there has always been a mechanism, but it was not |
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originally automatic. In RFC958, http://rfc.net/rfc958.html, there is |
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this reference |
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5.4. Leap Seconds |
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A standard mechanism to effect leap-second correction is not a |
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part of this specification. It is expected that the Leap |
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Indicator bits would be set by hand in the primary reference |
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clocks, then trickle down to all other clocks in the network, |
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which would execute the correction at the specified time and reset |
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the bits. |
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The newer NTP standard is now RFC1305, http://rfc.net/rfc1305.html. |
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>From my brief look it seems that the leap seconds are listed in a |
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file. The server then sets the leap indicator when needed. |
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> before NTP was widely used. |
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Not sure about that, but even the later standard is now 13 years old. |
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The original is 7 years older than that. I'd be surprised if a lot of |
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permanently connected sites, eg Universities, haven't been using it for |
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a long time now. However most home users wouldn't have had much use |
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for it before the growth of lower rate broadband services. |
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-- |
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Ian. |
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EOM |
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-- |
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