Re: [dnsext] Re: I-D ACTION:draft-vandergaast-edns-client-ip-00.txt

[Martin Barry <[e-mail]>]

$quoted_author = "Ted Hardie" ;
> 
> On Mon, Feb 1, 2010 at 10:45 AM, Nicholas Weaver
> <[e-mail]> wrote:
> 
> > Here's a concrete example, lets take imap.google.com (latency matters
> > for IMAP, bigtime...)
> 
> IMAP is not one of the store-and-forward bits of the email architecture;

I think he was addressing the "why not just use [HTTP feature X] to
redirect" comments.


> SMTP would be.  But the core question comes back to:  how does the
> DNS stack know that this application is one for which localization will
> be desirable, given that this is a decision made by the authoritative
> server?  Do you expect this to be opted-into for every query, or only
> for some?

My reading of it was those resolvers not near the edge they are serving
would opt-in for all queries.

 
> You don't actually know that--you're providing a response based on the subrange,
> but depending on the liveness of your load balancing and the caching
> implementation
> you could get a wide variety of results.  If I previously provided a
> single response
> based on the IP address of the querying server and now provide one based on
> the subrange being served, I might choose to lower the TTL to 0 in order to make
> sure that each subrange query is served "fresh", rather than from the cache

This has drifted away from being edns-client-ip specific, but...

Selecting a TTL will probably depend on how resilient each of the "local"
nodes is. Those using "dns tricks" should already have considered this in
their current implementations. 

cheers
Marty