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Adam -- DNS survey


The DNS (Domain Name System) is a distributed, hierarchical database which provides (among other things) the mapping between names and IP addresses for machine on the internet. It is a complicated and subtle system, and essential to the correct operation of almost every internet service. A collection of documents describing the purpose and mechanism of the DNS (including the well over 100 DNS-related RFCs) is here.

We are currently gathering data from the DNS, by performing zone-transfers of as many zones as we can, starting with the gTLD zone files, and working down the tree of delegations. We hope to use this data to:

  • analyze the content of the DNS (and compare it to the usage patterns);
  • evaluate some proposed improvements to the architecture of the DNS; and
  • experiment with aggressive caching and pre-fetching mechanisms.

You can help us!

If you are the administrator of a zone under a gTLD (COM, NET, ORG, COOP, &c.), and your servers do not generally allow AXFR requests, you can help us enormously by allowing zone transfers from

Our probe is polite - it learns which servers are permanently unreachable or refuse all AXFR requests and backs off rather than insistently querying them for large numbers of domains. If you've reached this page because you've seen an entry in your logs from our probe, we'd be delighted if you could either let us know that your servers will now accept requests from us, or send us a copy of your zone file by some other means.


Jon Crowcroft
Tim Deegan
Andrew Warfield