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

[Jim Reid <[e-mail]>]

On 2 Feb 2010, at 17:13, Nicholas Weaver wrote:

> You can easily do fallbacks for those who don't speak this EDNS0  
> option:  If you don't get a response on the first query, retry  
> without this option.  If that works, have your next 2-3 queries be  
> both (with and without).  If those two or three also fail, record  
> that authority as not supporting, and don't use the query in any  
> subsequnet responses
>
> Voila, you have fallback: only ever hits a timeout the first time  
> for authorities which can NOT respond to a request with an unknown  
> EDNS option, and even for those, its only 1 timeout latency and 2-3  
> extra queries from each recursive resolver which bothers with this  
> option.
>
>
> This is why the basic scheme is so beautiful: it does NOT require  
> changes to anyone who doesn't actually care about this option.  This  
> is the kind of thing EDNS options should be designed for: optional  
> behavior amongst a subset of the system.

So, your idea of optional behaviour in some circumstances is to  
increase DNS latency and generate extra queries. I see...