In message <[email protected]>, Curtis 
Villamizar writes:
> 
> In message <[email protected]>
> Mikael Abrahamsson writes:
>  
> > On Wed, 1 Aug 2012, Brian E Carpenter wrote:
> >  
> > > That's true. My point was that the CPE resolver will have to be upgraded 
> > > to support DNS64 for, and *only* for, IPv6-only hosts. How it knows 
> > > which hosts are IPv6-only is another mystery.
> >  
> > Indeed, I started a thread about this on v6ops the other day:
> >  
> > <http://www.ietf.org/mail-archive/web/v6ops/current/msg13581.html>
> >  
> > Seems there is no solution to this problem and I'm seem to be having 
> > trouble getting traction there that this might actually be a real problem 
> > that needs solving.
> 
> 
> Same answer as one given on that thread.  If a device can support
> IPv4, then use NAT4.  If a device can only support IPv6, then the
> DNS64 belongs on the IPv6-only device.  To that device all host return
> AAAA records, since the A records are translated into ipv4-in-ipv6
> space.  The CPE should be dual stack and be capable of both NAT4 and
> NAT64 translations to allow reachability into the IPv4 world.  This is
> simple.  As pointed out on the thread, a patch has already been
> submitted to android and some 3gpp phone already do DNS64.
> 
> If the CPE doesn't do NAT64, the packet will wander along some route,
> most likely the default route, until it either hits a NAT64 or runs
> into a black hole.
> 
> Propogating DNS64 translated address can cause severe problems and
> therefore should never leak outside the single IPv6 only host that
> needs it to get to IPv4 addresses.  DNS64 and NAT64 already exist for
> BSD and Linux (bind and pf for BSD, bind and linuxnat64 for linux).

DNS64 does not add synthesised addresses to existing AAAA RRsets.
IPv6-only nodes will not be able to connect to dual stack servers
as there is no IPv6 path.

> Curtis
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-- 
Mark Andrews, ISC
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