How to tell if something is anycasted?

bmanning at bmanning at
Wed May 17 14:45:41 UTC 2006

well Peter, ONE root server operator has that practice.  Others
have different practices regarding anycast.


On Tue, May 16, 2006 at 11:59:54PM -0700, Peter Boothe wrote:
> On Tue, 16 May 2006, David Hubbard wrote:
> > So I'm looking at a company who offers anycasted DNS;
> > how do I tell if it's really anycasted?  Just hop on
> > different route servers to see if I can find different
> > AS paths and then do traceroutes to see if they suggest
> > the packets are not ending in the same location?
> > >From my routers' perspective I don't see a difference,
> > but then I don't think I should, correct?
> If they conform to the convention that the DNS root servers practice, then
> a dig query from several locations should suffice.  Choosing an anycasted
> DNS root at random, you can do
> 	dig hostname.bind chaos txt
> And the response should include a line like
> hostname.bind.          0       CH      TXT     ""
> >From other locations, it might be "" or somesuch.
> If they don't do that, then you are stuck with more ad-hoc methods like
> traceroutes from many different locations, or checking out AS-PATHS in
> Routeviews and using your intuition.
> 	-Peter
> --
> Peter Boothe
> PhD Student                         "Young man, you think you're very
> Computer Science                    smart, but it's turtles all the way
> University of Oregon                down!"

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