Safari on IPv6 ?

Bernhard Schmidt berni at
Mon Feb 1 11:44:18 CET 2010

On Mon, Feb 01, 2010 at 11:21:53AM +0100, Marco Hogewoning wrote:

Note: this is only hearsay, some colleagues have this issue.

> This should be easy, however I can't seem to find the answer online as
> most articles are about turning off IPv6 instead of one. I noticed
> Apple's Safari 4.04 defaults to IPv4 instead of IPv6 when both A and
> AAAA are present. Now you can discuss wether this is a safe default or
> not, I would really like to know where the little button is to switch
> this behavior to AAAA first, which I recall used to be the case on
> earlier editions.

We have seen a similar behaviour with most applications after upgrading
to MacOS X 10.6. It seems that the mdns-responder (?) of the system
which is responsible for all DNS lookups is broken. It sends out both A
and AAAA queries at the same time, but only seems to accept the first
(successful?) response it gets.  I've even heard that some people see
the second UDP response from the cache is rejected with "Port

The effect is not a preference of IPv4, but no preference at all.
Extremely hard to debug.

Bugs have been filed with Apple several times, I can ask for the

Best Regards,

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