Safari on IPv6 ?

Sam Wilson Sam.Wilson at
Mon Feb 1 15:32:07 CET 2010

On 1 Feb 2010, at 13:22, Ron Broersma wrote:

> The confusing behavior you're seeing in OSX 10.6 is most likely the  
> mDNSResponder issue reported earlier by Bernhard.  Apple switched  
> to mDNSResponder for unicast DNS resolution in 10.6, but that broke  
> IPv6 address selection because mDNSResponder takes whatever is the  
> first response (A or AAAA) and drops (rejects) all other answers.   
> So, depending on how you ask, and depending on what address comes  
> back first, there is no way for the rest of the system or  
> applications to see all the responses and make appropriate address  
> choices.  This seriously impacts IPv6 interactions, because it no  
> longer deterministically prefers AAAA over A, but rather uses only  
> the response that arrives first.

Can you describe situations where you should expect multiple answers  
to have different information?  I don't think I understand what  
mDNSResponder is doing because in normal DNS, modulo times when  
information is changing, all answers should have the same data.

Sam Wilson
Network Team, IT Infrastructure
Information Services, The University of Edinburgh
Edinburgh, Scotland, UK

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

More information about the ipv6-ops mailing list