I am working on a multi time zone application (.NET 3.5). We are using the windows time zone database via the TimeZoneInfo class. All is well within our application, but we have noticed that the windows time zone database is different accross two machines (Windows 7 Ent/Windows Server 2003) that both have the Aug 2011 time zone patch applied (http://support.microsoft.com/?kbid=2570791)?
Can anyone suggest why this is the case? Two versions of windows, same time zone patch, same planet.
This isn’t strictly a programming question, perhaps I should post it elsewhere?
It turns out that the differences in the database are there for backward compatibility. The older OS keeps records for time zones that were in use when it was released but have since become obsolete. The newer OS ignores historical time zones. The upshot is that the date time conversion results are the same on either OS. Happy days.
As an aside, there is a minor (well very minor to us anyway) discrepancy in that the Middle Eastern Time DST for 2009 starts Saturday 23:59 on Win Srv 2003 but Sunday 00:00 on Win 7. Looks like a mistake from MS to me.