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Re: Geographic map of IPv6 availability

  • From: Mark Andrews
  • Date: Mon Oct 15 07:36:44 2007

In article <[email protected]> you write:
>On 15/10/2007, at 8:24 PM, Martin Hannigan wrote:
>> [moresnip]
>> The way I read the portion of the thread related to resolver behavoir
>> was that the resolver behavior was being discussed. Not the client.
>> The resolver should have an attribute to select the preference between
>> A vs. AAAA. Otherwise, it's setting network policy through code.
>> My question was if there is an option to adjust this, where is it? I
>> don't see it. I'm not a BIND uber-expert. If there is no option, there
>> quite possibly ought to be one.
>I guess the question could also be asked as to whether BIND honours  
>the host's configuration of the address selection policy - which  
>seems more likely than implementing it itself.
>For those who missed it - OS level address selection policy won't  
>apply to BIND without specific code, as BIND is a recursive resolver  
>so won't be calling getaddrinfo(3).
>Nathan Ward

named actually measures the response times to individual addresses
and uses those to determine which servers to query.  Named also
uses what addresses it has before attempting to determine if there
are alternate addresses.

Address selection policies are kind of meaningless in this environment.

But what really trumps all of these is getting rid of firewalls
that don't handle EDNS queries.  These along with nameservers that
fail to respond to EDNS queries slow up the resolution process much
more than picking a sub-optimal addresses to query.