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Re: How to tell if something is anycasted?
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 @f.root-servers.net hostname.bind chaos txt And the response should include a line like hostname.bind. 0 CH TXT "pao1b.f.root-servers.org" >From other locations, it might be "sfo2c.f.root-servers.net" 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!" http://www.cs.uoregon.edu/~peter