I think it’s clear that DNS won’t support all leap second use cases, but that
it may provide a high reliability / low latency method for some specific
purposes. Here is PHK’s specific example:
$ dig +short leap.net-tid.dk a | ./leapdecode.py
248.40.141.250 -> OK 2015 7 +35 +1
(dig might be useful for some script, but most usage will be more direct
methods, of course) Leapdecode.py is PHK’s crc8() and dec() functions with:
for l in fileinput.input():
print("%s -> %s" % (l.rstrip(), dec(l)))
With a wayward assert commented out this then does something useful with
nonsense inputs:
$ dig +short google.com a | ./leapdecode.py
74.125.224.97 -> BAD 2027 12 +120 +0
74.125.224.101 -> BAD 2027 12 +120 +0
74.125.224.102 -> BAD 2027 12 +120 +0
…
This is turning into a cottage industry and I doubt I’m alone in trying
variations myself on this end:
$ dig +short next.leapsec.com a | ./leapdecode.py
248.40.141.250 -> OK 2015 7 +35 +1
and
$ dig +short next.leapsec.com aaaa | sed -e 's/:\(.\):/:0\1:/' -e
's/::/T/' -e 's/:/-/' -e 's/:/-/' -e 's/$/Z/'
2015-06-30T23:59:60Z
The quasi-readable IPv6 format we’ve been tossing around can be replaced with a
more fully featured version of PHK’s Bulletin C, perhaps including DUT1,
significantly expanded ranges of applicable dates and leap second tally, etc.
The next.leapsec.com <http://next.leapsec.com/> address could be coupled with
prev.leapsec.com <http://prev.leapsec.com/> and other options. Etc and so
forth.
And as Steve points out, the tzdist discussions would support other use cases.
Rob
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