[tz] America/Metlakatla now follows Alaska

[TechOps]

thanks for the great info all! And yea, I'm not sure town leadership
thought they'd have to do more than just change their clocks.



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AKTechOps <http://serrc.org/techops> | techops at serrc.org | 907.523.7290

On Tue, Nov 10, 2015 at 10:49 AM, Matt Johnson (PNP) <
matt.johnson at microsoft.com> wrote:

> Also keep in mind that a large number of mobile devices (esp. phones) do
> not actually use the device's location information to set the time zone,
> but rather use the signals provided by the mobile carrier (such as NITZ).
> https://en.wikipedia.org/wiki/NITZ
>
> These settings differ for individual cell towers and can sometimes be
> inaccurate, as they send only the current standard time offset from utc,
> and a DST offset if and when DST is in effect.
>
> You could find out which mobile carriers have cell towers in the area and
> ask them to update the time zone to include the DST offset.  Doing so would
> likely cause phones that use these signals to pick Alaskan time.
>
> -Matt
>
> -----Original Message-----
> From: tz-bounces at iana.org [mailto:tz-bounces at iana.org] On Behalf Of Guy
> Harris
> Sent: Tuesday, November 10, 2015 10:41 AM
> To: TechOps <techops at serrc.org>
> Cc: Time Zone Database <tz at iana.org>
> Subject: Re: [tz] America/Metlakatla now follows Alaska
>
>
> On Nov 10, 2015, at 10:12 AM, TechOps <techops at serrc.org> wrote:
>
> > thanks for the reply Guy, and sorry for being vague. By Apple's servers
> I mean whatever servers reply to an out-of-the-box iPad or Mac when it
> tries to set its timezone based on location.
>
> You're assuming that what servers are involved there, if any, need to have
> the time zone rules up to date.
>
> As far as I know, setting the time zone based on location is done by:
>
>         the machine using Location Services to find out where it is -
> that's done using GPS if it's available, and otherwise done, I think, by
> looking around for Wi-Fi access points and figuring out where you are based
> on that:
>
>
> https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fWi-Fi_positioning_system&data=01%7c01%7cmatt.johnson%40microsoft.com%7ca58ed9d6211d4fbc46e808d2e9fea391%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=5ahoEDDu%2bx%2bkNlftdyzdwScRvUw%2bQmWKk%2bwowRRDgNY%3d
>
>         the machine then looking up that location in a set of maps of tzdb
> zone boundaries, which might be stored on the machine or might be obtained
> from a server.
>
> The first of those operations only involves servers for the Wi-Fi
> mechanism, and doesn't involve time zones at all, only a database of Wi-Fi
> networks, so *those* servers don't need to be updated.
>
> The second of those might involve servers to map a location to a tzdb
> zone, but
>
>         1) it might not, if the maps are stored on the machine;
>
>         2) even if it does, only a tzdb change involving changes to zone
> boundaries, including the creation of a new tzdb zone, would have to get
> propagated to the server.
>
> OS X, iOS, tvOS, and any other Darwin-based OSes from Apple all use the
> tzdb internally, so it's not the servers that need updating, it's the OS on
> the *clients*.
>
> > Basically I'm wondering what the standard trickle-down duration is...
> days, weeks, or months.
>
> Well, as I said, it needs to trickle down to your machines, not to the
> servers.
>
> There's no standard duration for Apple's OSes, as they're currently not
> set up to provide tzdb updates outside of software updates, so the
> trickle-down duration (the time between a tzdb release and its appearance
> in a Darwin-based OS) depends on
>
>         1) how long it takes Apple to get a tzdb release into an OS
> dot-dot release;
>
>         2) how long it takes that release to come out, as it has a lot
> more in it than just a tzdb update.
>
> Note also that if the machine isn't running an OS that gets updates that
> include tzdb updates, it won't get updated.  I don't know whether they are
> included in security updates, but, if they don't, you won't get updates for
> Macs running anything other than El Capitan, and I don't know whether iOS
> gets security updates for major releases before the current release, so
> machines running iOS 8 or earlier may not get updates.
>
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