[VoiceOps] DST handling

Peter Beckman beckman at angryox.com
Thu Nov 5 17:39:51 EST 2009

On Thu, 5 Nov 2009, David Hiers wrote:

> I thought that ntp doesn't know or care about DST.  It works in UTC,
> and the OS is responsible for any DST adjustment it wants to make.
> If you're an hour (3600 seconds) off in NTP, and it takes 2000 seconds
> to adjust for every second you are off, it'll take 7200000 seconds to
> get back on track, which is about 83 days.  Seems kinda long...

  That's the default.  You don't want NTP to change a production server from
  1pm to 2pm in one giant leap.  That would screw a lot of things up,
  especially on a VoIP server that does billing!  By spreading an hour
  change over 83 days, it makes sure you don't totally screw up your

  Ideally, if it were off by an hour, you'd take it out of production,
  update the clock, then put it back in.  If you couldn't, NTP's solution is
  a pretty good balance.

  Ideally, NTP keeps your clock in sync +/- 1 second at all times, and since
  the OS does the translation from UTC to your server time zone, there will
  never be a time that it is an hour off, unless all of your time servers go
  down (or your network does).

  If we all worked on UTC and all had all of our clocks synced, we would all
  have a LOT easier time correlating CDRs between ourselves and our

  That brings up another question -- do you display the start time or end
  time of the call?  I display start time, but I'm curious if there is a
  standard among providers, both retail and wholesale.

Peter Beckman                                                  Internet Guy
beckman at angryox.com                                 http://www.angryox.com/

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