Google no longer returning AAAA records?

Erik Kline ek at
Fri Apr 17 05:45:25 CEST 2015

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}.

We almost never know what X or Y are.  We only detect that there
appears to be a problem.

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