The best network for dns is anycast based.
See Anycast - Three Reasons Why Your DNS Network Should Use It | Information Security News, IT Security News & Expert Insights: SecurityWeek.ComAnycast allows multiple, identical, globally deployed DNS servers to advertize the same IP address. For all intents and purposes, the same server exists in dozens or hundreds of places simultaneously. When an Internet user looks up your domain name, they find the Anycast instance topologically closest to themselves. Usually, there's a correlation between network topology and physical geography. A user in Madrid might find and use a node in London or Amsterdam, while a user in Mexico might find themselves directed to a node in California.
However, it is very costly to deploy your own anycast based dns server. So most people either select anycast based dns provider such as Amazon or deploy their own in two or three continent. Personally, I've purchased small XEN based VPS servers and they are located in London, Singapore, USA (TX), and Amsterdam city. But, I'm planning to switch to Amazon new cloud and anycast based server to save money.