How to tell if something is anycasted?

Steve Gibbard scg at
Wed May 17 18:11:42 UTC 2006

On Wed, 17 May 2006, Martin Hannigan wrote:

> And there are many, with many TLD's.
> (rough counts)
> provider/tld's
> 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
> anycasted.
> 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 

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.


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