geoip-enabled authoritative dns server is quite easy to find - bind9 with patch can do it, powerdns as well. but the problem starts when server receives DNS query from global public resolvers like google's 8.8.8.8. the request might come from ip in completely different geolocation location than the actual user. queries from google can carry that information.
do you have any experience with running servers that handle edns-client-subnet and provide answers depending on the geolocation of the client? what [reasonably stable] open source dns servers provide that functionality?
i've found so far one - gdnsd.org but i'm curious to hear about your experience and alternatives.
thanks!
The experience is that you will not handle anyone doing company networks for larger companies or VPN to start with - the idea of geolocating at the DNS level is a hack at best.
I have a room full of people in Poland that would have all traffic routed to Toronto if I would not - ah - "interpret" the regulations of my business partner and not put in the proxy information. Whenevr I travel, my traffic routes through my office via VPN - have fun geolocating me in France when the traffic originates in Poland.