what's the best solution and product to build DNS system in global network?

Answer 1

linux, freebsd, unix any good server software and "bind" is as good as any dns software, easy to use, easy to setup, easy to manage. Since these are all light systems just about any computer would work obviously servers with redundancy are better.

To do it correctly you would have to have two machines on two different class C networks so there would always be "fall-over" should one fail or the network become unavailable. (You wouldn't run these at the same physical location either - one east coast, one west etc)

Answer 2

freebsd and bind (named) running as a non-root user in a chroot jail