[Osmf-talk] Encouraging the expansion of GeoDNS enabled tile serving?

Tom Hughes tom at compton.nu
Thu Nov 15 13:42:52 UTC 2012

On 15/11/12 13:28, Joseph Reeves wrote:

> > What sort of documentation? You seem to have already found most of
> > the relevant stuff.
> Ok, I didn't know if there was any additional technical documentation or
> any more usage stats available. Presumably the DNS bit is pretty
> straightforward, and members of the CDN just mirror the original OSM
> database.

There's no mirroring as such - the servers just run squid with the 
primary tile server as the upstream server.

> I would be interested in how a user's tileserver is determined, however;
> if I'm physically halfway between Sjöbo and Brisbane is my tileserver
> decided by a calculated round-trip time to a server, or does it rely on
> a simple rule such as "you're in India, so your tiles come from Sweeden"?

Basically it is determined by this script:


based on the rules we specify:


So we can restrict a server to only serve specific countries no matter 
what, as we have for example with the Brisbane server.

All else being equal the final determinant is distance.


Tom Hughes (tom at compton.nu)

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