Google no longer returning AAAA records?

Lorenzo Colitti lorenzo at
Fri Apr 17 08:24:31 CEST 2015

And in the meantime, accept that the users of that operator's network
cannot reliably reach our services?

If you were a user of that operator, I suspect you wouldn't like that. I
suspect you especially wouldn't like it if you called the operator and they
told you there were no problems, and most websites work fine.
Unfortunately, in our experience, both happen routinely. Often operators
will contact us and claim there is no problem in the network, and most of
the time it turns out that there was a problem they didn't know about. Once
the claim was made that "this is an IPv6-only network, so IPv6 must be
working". Unfortunately that wasn't true either.

If an operator is monitoring IPv6 traffic levels, it will be pretty clear
if Google stops serving AAAA records to their resolvers. If they're not
monitoring IPv6 traffic levels, then chances are they're not monitoring
reliability, because it's much easier to monitor traffic than to monitor

There's also the question of how whether it's reasonable to expect websites
to to reduce the reliability of their services in order to fix problems in
other networks that they have no control over. Remember, IPv6 brokenness
was one of the main reasons it took so long for popular websites to enable

On Fri, Apr 17, 2015 at 12:28 PM, Brian E Carpenter <
brian.e.carpenter at> wrote:

> On 17/04/2015 15:17, Erik Kline wrote:
> > On Thu, Apr 16, 2015 at 7:41 PM, Phil Mayers <p.mayers at>
> wrote:
> >> On 16/04/15 01:57, Lorenzo Colitti wrote:
> >>
> >>> For the avoidance of mystery: Google performs measurements of IPv6
> >>> connectivity and latency on an ongoing basis. The Google DNS servers do
> >>> not return AAAA records to DNS resolvers if our measurements indicate
> >>> that for users of those resolvers, HTTP/HTTPS access to dual-stack
> >>> Google services is substantially worse than to equivalent IPv4-only
> >>> services. "Worse" covers both reliability (e.g., failure to load a URL)
> >>> and latency (e.g., IPv6 is 100ms worse than IPv4 because it goes over
> an
> >>> ocean). The resolvers must also have a minimum query volume, which is
> >>> fairly low.
> >>
> >>
> >> Lorenzo,
> >>
> >> Thanks for the response.
> >>
> >> Do you know if Google have given any thought as to how long they might
> find
> >> it necessary to take these measures? Years, indefinitely?
> >>
> >> Just curious.
> >
> > It seems to keep on finding things, so...
> But the incentive is wrong. Forcing users to drop back to IPv4 offers
> no incentive to fix the IPv6 problem. The correct incentive would be to
> tell an operator that they will be blacklisted unless they fix {X and Y}.
>     Brian
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