Google no longer returning AAAA records?

Ca By cb.list6 at
Fri Apr 17 16:55:49 CEST 2015

On Thu, Apr 16, 2015 at 11:24 PM, Lorenzo Colitti <lorenzo at>

> 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
> reliability.
> 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 IPv6.

I agree with Google's approach for now.

But eventually it will have to be re-visited since Google represents a huge
amount of traffic, pulling back AAAA and sending that huge amount of
traffic to a CGN that is not dimension for it.... you are going to have a
bad time.

And, AFAIK, these measurements and adjustments are not real-time... so they
blow up a CGN ... they wont automagically roll back for a while.  So,
Google AAAA magic becomes a DDoS of sorts.

Maybe i am wrong.


> 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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