Yesterday's Windows update causes IPv4 to be default

Dick Visser visser at
Thu Nov 15 12:09:13 CET 2012

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.
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.

Dick Visser
System & Networking Engineer
TERENA Secretariat
Singel 468 D, 1017 AW Amsterdam
The Netherlands
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