Re: [BEHAVE] using IPv4-mapped DNS/DNS64 resolvers for dual-stack/IPv6-only hosts

Late catch-up with one comment on the approach:

if a dual stack host sends a query to first DNS (::ffff:192.0.2.1) but
fails to get any resultsr, it will failover to the second DNS and
there will be the same problem that traffic will be translated via
NAT64?

Thanks,
Zhen

On Sat, Feb 13, 2010 at 4:00 AM, Dan Wing <dwing@cisco.com> wrote:
> A few weeks ago there was an active thread on BEHAVE and 3Gv6@ietf.org,
> worrying about how a network containing a mix of dual-stack hosts and
> IPv6-only hosts would work.  Ideally, to prevent unnecessary address family
> translation, the dual-stack hosts should use a 'normal' DNS resolver and the
> IPv6-only hosts should use a DNS64 resolver.  However, it is difficult to
> detect if a host is dual-stack or is IPv6-only.
>
> So, I wrote an Internet Draft describing details of several approaches that
> had been discussed on the mailing list, and attempted to provide a list of
> advantages/disadvantages to each.
>
>
> While writing them down, I came up with another approach which uses an
> IPv4-mapped address in the list of IPv6 DNS servers.  An IPv6-only host cannot
> use that address, so it would use the next DNS server on the list; a
> dual-stack host can use such a DNS server.  Details are in:
>
> http://tools.ietf.org/html/draft-wing-behave-dns64-config-02#section-3.1
>
> Please comment on this approach.  For whatever it's worth, the idea seems to
> work.
>
> -d
>
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