Late Wednesday evening, Google employees posted an “Internet-Draft” outlining proposed changes to the DNS protocol that allow authoritative DNS servers to see the addresses of clients. This way, geographically distributed content delivery networks can tailor their answers to a specific client’s network location. So a client from California would talk to a server in California, while a client in the Netherlands would talk to a server in the Netherlands.
Currently, authoritative DNS servers don’t see the client address, only the address of the resolving server that is typically operated by the client’s ISP. So in the current situation, if our Californian and Dutch clients both use a DNS resolver in New York, a location-optimizing authoritative DNS server would give them both the addresses of servers in or around New York. By including the client’s address in the request, the authoritative server can send a better response and improve the subsequent interactions between the client and server because the request/response round-trip times across the network are shorter.