Google no longer returning AAAA records?

Brian E Carpenter brian.e.carpenter at
Fri Apr 17 22:35:10 CEST 2015

On 17/04/2015 18:24, Lorenzo Colitti wrote:
> And in the meantime, accept that the users of that operator's network
> cannot reliably reach our services?

I understand the dilemma. But if you don't make it easy for the operator
in question to know that they have a problem, it will definitely not get
fixed. Please think about ways to do that.

Ignatios said:

> I suspect Google will change their rule to be protocol independent
> in the future... if v6 is better than v4 for you, they won't give
> out A records to your resolver ;-)

I like that thought.

Scott said:

> Neither Lorenzo nor Erik should ever have to buy their own beer ever again IMO. 

In case there's any doubt: yes, I greatly appreciate your efforts, too. Thanks both.


> 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.
> 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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