The answer to above question used to be difficult. You had to be an expert to find out the answer. And unfortunately, this is not something that average internet users care about. Playing with dnstraceroute tool (see project on GitHub), I noticed it is a common practice among service providers to divert outbound DNS traffic to their local DNS servers. So If you thought you are using Google’s Public DNS Server or Verisign‘s, there is a good chance that your DNS traffic is in fact being served by ISP’s local resolver.