[dns-operations] How to get the anycast networks?
Patrick W. Gilmore
patrick at ianai.net
Sun Oct 14 11:34:33 UTC 2012
On Oct 13, 2012, at 05:51 , pangj <pangj at riseup.net> wrote:
>> An anycasted DNS only helps, if your 'other infrastructure', e.g. your
>> webservers, are also setup 'around the world' to keep the distance low.
>> What problems do you think anycast will solve?
> We are a small CDN company so we want the anycast DNS for our customers.
While people have been debating whether this is useful, I note no one has actually answered your question.
First, is it possible to anycast your name servers (or anything else) without your own ASN. You'll need a /24 (at least) of your own, and you'll need to convince multiple providers to announce it, but it can be done.
This will result in your prefix showing up as "inconsistent origin". That doesn't mean anything, and doesn't break anything. That won't stop some people telling you it is broken, so be prepared.
Please note that though it /can/ be done, think carefully about whether it /should/ be done. Anycast is useful, a powerful tool in the right hands, but it can also have unintended consequences. For instance, I have seen users in London go to anycast instances in Tokyo because of poor design & deployment. Of course, the same thing can - will - happen with unicast. But you do not want to go through the time & effort of anycasting your name servers for zero performance gain, or worse.
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