[ntp:questions] Purpose of a leap second file?
David J Taylor
david-taylor at blueyonder.co.uk.invalid
Thu Feb 16 06:53:49 UTC 2012
"A C" <agcarver+ntp at acarver.net> wrote in message
news:4F3CA0A1.5070506 at acarver.net...
> Given the recent thread here about the upcoming leap second, I wanted to
> know what additional service/value the leap second file provides that
> isn't handled by ntpd receiving a message to add or remove a second. I
> understand the generic ntpd documentation includes a flag to add a leap
> second so it seems that the leap second file isn't necessary (and that's
> also borne out in searches) but it must provide something otherwise it
> wouldn't exist. The documents mention a "graceful" handling, but what
> does that mean exactly?
The file isn't required for Windows ports of NTP, and I don't recall ever
explicitly updating the file (if it existed) for either of my FreeBSD
servers. Presumably, there is output in the GPS stream signaling the
possibility of a leap second, and/or the GPS devices produce a 61st second
at the appropriate time.
I recall a posting somewhere showing that the different GPSs behaved in
slightly different ways in this respect. Last leap-second I only had one
GPS - now I have four so it could be fun watching them argue!
Perhaps having this file would avoid such difficulties? Where would I
place the file for FreeBSD, and can Windows use it?
More information about the questions