Yesterday's Windows update causes IPv4 to be default

Brian E Carpenter brian.e.carpenter at
Thu Nov 15 17:55:21 CET 2012

On 15/11/2012 11:09, Dick Visser wrote:
> On 14 November 2012 23:20, Dan Wing <dwing at> wrote:
>> The URL it tries to visit is, and
>> searching the Internet for that FQDN yields some details of how it
>> works.  If it can't retrieve the expected text at that URL, Windows
>> will order IPv6 to the bottom of its address preference table (by
>> tweaking its internal RFC3484 rules).  The success (or failure) to
>> get to that IPv6 site is remembered for that network for 30 days,
>> and then re-tested.  I don't know how to encourage it to try a
>> fresh test, but there must be a registry setting to force that to
>> occur.
> It looks like there is, see attached regedit screendump.

Thanks for that. It looks as if one should clear
EnableActiveProbing to get rid of this feature.


> It differs from the one in the blog post, in that there
> are v6 versions of some parameters.
>>From the looks of it, it allows you to specify which host names,
> addresses, and web server file paths should be used for the probe.
> So while the defaults might be sucky, you are able to change them.
> ------------------------------------------------------------------------

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