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Many people  configure their computer or router to use a specific DNS server that  they prefer (such as Google DNS which is found at 8.8.8.8). The  expectation is that the server at 8.8.8.8 provides your DNS services,  but that isn't what really happens. If it did, that server would be  swamped with requests. Instead, it hands your request off to another  server that's part of a large group of servers that it controls. By  doing this, no one server will be completely overwhelmed with requests.
The  data that's reported here shows the identity of the server that  actually processes your requests. You can verify that it's being run by  an organization that you trust. We also check the reputation of each  server that we report to see if it has been flagged by people for doing  questionable things.
This also explains why if you check your DNS  server multiple times using this service you'll often receive different  IP addresses. This happens because each IP address represents a  different server in the "group".