AAAA's for www.netflix.com

Fri Jun 8 01:19:10 UTC 2012

On Thu, Jun 07, 2012 at 04:43:41PM -0700, David Temkin wrote:
> What do you mean?  www.netflix.com is dual stacked, which represents
> availability of our website (and PC/Mac streaming clients) to100% of our
> users who have IPv6.

The zero TTL on the CNAME an AAAA RRs makes www.netflix.com
zero-stacked at least for some resolvers:

$ dig @pdns3.ultradns.org www.netflix.com. A +norec +short
wwwservice--frontend-313423742.us-east-1.elb.amazonaws.com.
$ dig @pdns3.ultradns.org www.netflix.com. AAAA +norec +short
dualstack.wwwservice--frontend-313423742.us-east-1.elb.amazonaws.com.
$ dig @pdns3.ultradns.org www.netflix.com. ANY +short +norec
$

Resolving www.netflix.com using ANY RRtype fails with an empty answer
section in the DNS response.

This DNS trickery seems to be from the "taking a shower, trying not
to get wet" department. And has adverse effects in corner cases. While
playing around, I had periods of time where I couldn't resolve the FQDN
at all, possibly due some caching of the empty response.

Best regards,
Daniel

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