Question to Google
bortzmeyer at nic.fr
Mon May 15 12:43:59 UTC 2017
> Unfortunately, every time we've looked at the data, the
> conclusion has been that it would cause unwarranted user
> impact. IIRC the most recent blocker was a major US ISP whose
> clients would experience breakage if even just one NS record
> was dual-stacked.
There are many zones (including your isc.org) that have several name
servers dual-stacked, and they didn't notice a problem. Furthermore,
since the DNS is a tree, resolution of google.com requires a proper
resolution of the root and .com, both having IPv6 name servers.
So, this answer is at least insufficient.
More information about the NANOG