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Re: How to tell if something is anycasted?

  • From: Martin Hannigan
  • Date: Wed May 17 17:22:38 2006

At 02:11 PM 5/17/2006, Steve Gibbard wrote:

On Wed, 17 May 2006, Martin Hannigan wrote:

And there are many, with many TLD's.
(rough counts)


ISC 19
PSG 23
DEC 10

Note: There is cross servicing of TLDs counted above.

Some numbers may seem low since there seems to be some bit of
obfuscation. Or perhaps not and I just haven't confirmed.

Some are anycasted, some appear to be physical separations, and some
appear to be nested and anycasted i.e. multiple names for the same domain

I think naming is a bad choice because it's costly to the users and opens
the root up to custom configuration by customers which I think is bad.

Tagging the route with a community containing the ISO corresponding country
could be interesting for location purposes, but of course, that's already
been thought of. :)
Of Marty's list above, only UltraDNS and PCH are anycast (there are several other anycast networks hosting TLDs that aren't on Marty's list).
Right. They start to get smaller in numbers and less interesting.

The numbers there look odd to me. My data is a six months old (I really need to rerun my script and regenerate it), but my list of /24s and the TLDs they host is at:

I assume that in most cases a /24 with multiple DNS server IP addresses being authoritative for TLDs is all run by one entity in a common location or set of locations. UUNet is an exception to the location assumption.

The difference is that you are following the network and I'm following the

Thanks for sharing your data.


Martin Hannigan (c) 617-388-2663
Renesys Corporation (w) 617-395-8574
Member of Technical Staff Network Operations
[email protected]