Re: Anycast provider for SMTP?

["Joe Abley" <jabley () hopcount ca>]

On 19 Jun 2015, at 8:12, Christopher Morrow wrote:

> On Fri, Jun 19, 2015 at 7:19 AM, James Hartig <fastest963 () gmail com> 
> wrote:
>
> > Just curious, how does DNS load balancing work if people are using
> > 8.8.8.8/208.67.222.222 or basically any public resolvers that cache 
> > and

If the client that performs the upstream query within the 
8.8.8.8/whatever infrastructure is close to you for some meaningful 
interpretation of "close" then you still get an answer that is 
(effectively) localised for you.

If the resolver infrastructure is sufficiently far that what is good for 
it is not good for you, then the deployed (if not quite standardised) 
answer is edns-client-subnet: the resolver infrastructure you're using 
embeds your client address in its upstream query. The authority servers 
can then localise a response (and scope it) as being suitable for you, 
not the resolver in general.

  http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-02

There are privacy concerns, here. But we might posit that you've already 
in the business of trading privacy for convenience if you're using a 
public resolver.

> don't know exactly, but you might get some interesting clues from the
> f-root or as112 designs, eh?

Root servers and AS112 servers don't steer clients towards content 
according to where they are. They give consistent answers for all 
queries, regardless of where they came from.


Joe