How to tell if something is anycasted?

Martin Hannigan hannigan at
Wed May 17 21:21:20 UTC 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)
>>UDNS 48
>>ISC 19
>>PCH 8
>>PSG 23
>>UUNET 61
>>RIPE 87
>>DEC 10
>>NIC.FR 71
>>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
                                                hannigan at  

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