On Mon, Jan 4, 2016 at 2:48 PM, <valdis.kletni...@vt.edu> wrote: > On Mon, 04 Jan 2016 17:23:20 -0500, Christopher Morrow said: > > https://developers.google.com/speed/public-dns/faq?hl=en > > > > there I asked jeeves for ya! > > > > So in how many of the 196 or so extant countries does 8.8.8.8 resolve > to > > > a host which, when it sends a query up the chain, appears to be in the > > > same country as the machine that made the original query? > > With 43 subnets for servers and only 13 unique airport codes, the > conclusion > is that without additional fun and games, locating based on the DNS for > 8.8.8.8 > will be incorrect for *most* countries. Probably gets the continent right.
If you're load-balancing by country, you've already lost. It turns out the USA has more users than Luxembourg, Samoa, Monaco, Bermuda, and Andorra *combined*. On Mon, 04 Jan 2016 14:17:56 -0800, Owen DeLong said: > > Further, 8.8.8.8 actually fully supports EDNS0 Client Subnet capability, > so > > if the geo-IP balancer in question wants, they can eliminate the failure > mode > > you are describing in that case. > > Which only helps for people using 8.8.8.8. Client Subnet does help the > issue, > but it doesn't actually fix it until support is near ubiquitous across > intermediate nameservers that have clients in other geographic locations... > > (I believe that the fact that Google found a need to create EDNS0 Client > Subnet *at all* is proof that using the DNS address for localization is > problematic...) > > And again - it's still something that needs work upstream to support, and > you *still* have to deal with the case where the intermediate DNS server > doesn't do Client Subnet. > Not all auth servers need to support Client Subnet... just those that want to do DNS-based load-balancing in a more fine-grained level than already achieved by Google's multiple datacenters. And while I don't know what software most companies use for their DNS-based load-balancing, I'd guess that adding Client Subnet support is a minor feature request relative to the other required logic. Damian