Google no longer returning AAAA records?

Brian Rak brak at
Thu Apr 16 22:06:47 CEST 2015

On 4/15/2015 8:57 PM, Lorenzo Colitti wrote:
> On Thu, Apr 16, 2015 at 4:56 AM, Brian E Carpenter
> <brian.e.carpenter at <mailto:brian.e.carpenter at>> wrote:
>     I suggest checking if any of your affected users have broken 6to4
>     setups,
>     and that you are applying the relevant mitigations in RFC 6343.
>     MTU size issues and high latency have also both been mentioned as
>     possible reasons for the mysterious AAAA blacklist.
> 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.

As it turns out, we have a configuration error that's pushing out a a 
default route via radvd to machines that don't have a publicly routable 
IPv6 address assigned.  I suspect this is at least partially responsible 

More information about the ipv6-ops mailing list