All,
With the recent announcement of Google's public DNS servers, I am worried about operators of CDN who may rely on DNS queries for geo-location (Akamai comes to mind).
Today it is reasonable to assume DNS queries from ISP1's name servers (or address block in general) are probably from a client within the ISP1 network. With public DNS servers it gets a whole pile harder.
A issue I saw first hand is when I had statically set my DNS resolvers to ISP1 servers and then changed to ISP2. For many months everything went okay but then one day iTunes stopped working. It was not that ISP2 was blocking access to their DNS resolvers, but that the Akamai cluster that queries to the ISP2 resolvers was not advertised into the ISP1 network (rightly or wrongly). More importantly, ISP1 had Akamai servers of their own which I had been bypassing.
I think this is something for the community to carefully consider, especially given how CDN like Akamai can dramatically reduce traffic across peering links for a number of NZ ISP.
I'm not trying to condone the idea of public DNS servers or comment on the motivation behind Google and others operating them, but just focus on the impacts.
Does any one else see a cause for concern?
-David M
