David J Taylor wrote:
So what happens on a PC running just e.g. FreeBSD? Is the BIOS clock
always kept in UTC? Or local time?
I'm interested to know what will happen when I next reboot my
FreeBSD/GPS stratum 1 server, which has been up since the end of
January when we were on winter time (i.e. UTC here)!
I don't know if there is a default for FreeBSD. The Linux installers
normally ask the user to select between UTC and local time, this setting
is kept somewhere (e.g. in /etc/sysconfig/clock), and the clock is set
and read accordingly.
However, the "setting to UTC" only fixes the issue when having multiple
systems all using that (e.g. more than one Linux partition).
When Windows is involved, there will always be difficulties.
It is best not to use the CMOS clock to carry a time setting over
between reboots. It is only accurate to the nearest second anyway, i.e.
almost completely useless.
Sync the clock using "ntpdate" from a nearby NTP server.
> Yes, I was also in a network management role at the time, and I don't
recall it being an issue in the UK.
Of course the UK did it differently. But at that time (95/96) the rules
in the UK and Europe were aligned.
They still are different from the US rules.
In 2002 the rules were changed again, but they still aren't uniform
around the world.
Just use Google to find some information about DST, there is plenty to
read, and after a while you start realizing that it is a can of worms...
And indeed, leap seconds are yet another issue. When we had one on
31-12 it seriously setup the NTP "network" as it had not happened for a
long time, and thus many implementations had never seen one.
Rob
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