A proposal to extend the DNS protocol
Today a group of DNS and content providers, including Neustar/UltraDNS and
Google are publishing a
proposal to extend
the DNS protocol. DNS is the system that translates an easy-to-remember name like
www.google.com to a numeric address like 74.125.45.104. These are the IP addresses that
computers use to communicate with one another on the Internet.
By
returning different addresses to requests coming from different places, DNS can be used to
load balance traffic and send users to a nearby server. For example, if you look up
www.google.com from a computer in New York, it may resolve to an IP address pointing to a
server in New York City. If you look up www.google.com from the Netherlands, the result could
be an IP address pointing to a server in the Netherlands. Sending you to a nearby server
improves speed, latency, and network utilization.
Currently, to
determine your location,
authoritative
nameservers look at the source IP address of the incoming request, which is the IP
address of your DNS resolver, rather than your IP address. This DNS resolver is often managed
by your ISP or alternately is a third-party resolver like
Google Public DNS. In most cases
the resolver is close to its users, in which case the authoritative nameservers will be able
to find the nearest server. However, some DNS resolvers serve many users over a wider area. In
these cases, your lookup for www.google.com may return the IP address of a server several
countries away from you. If the authoritative nameserver could detect where you were, a closer
server might have been available.
Our proposed DNS protocol extension
lets recursive DNS resolvers include part of your IP address in the request sent to
authoritative nameservers. Only the first three octets, or top 24 bits, are sent providing
enough information to the authoritative nameserver to determine your network location, without
affecting your privacy.
The Internet-Draft was
posted
to the dnsext mailing list today, and over the next few months our group hopes to see this
proposal accepted as an official Internet standard. We plan to continue working with all
interested parties on implementing this solution and are looking forward to a healthy
discussion on the dnsext mailing list.
(Updated 24 Jan 2011
to fix broken links)By Wilmer van der Gaast and Carlo Contavalli on behalf of the Google
Public DNS team
