Re: www.RT.com bad dns record

[Baldur Norddahl <baldur.norddahl () gmail com>]

On 2016-07-08 04:33, Matt Palmer wrote:
> On Thu, Jul 07, 2016 at 06:36:23PM -0700, Ca By wrote:
> > On Thursday, July 7, 2016, Spencer Ryan <sryan () arbor net> wrote:
> >
> > > Dotted-quad notation is completely valid, and works fine.
> > >
> > > https://en.wikipedia.org/wiki/IPv6_address#Presentation
> > >
> > > http://[::ffff:37.48.108.112] loads fine in my browsers.
> > It may be legit on your network, but people generally don't do that.... If
> > they publish a aaaa record, it usually has a legit v6 address in it.
> That is a legit IPv6 address.

No it is not. It is a format intended to be used only within a process 
to store IPv4 addresses in a single common data structure for IPv4/IPv6 
or for use in a socket API so a combined IPv4/IPv6 interface can be 
provided. There is no requirement that other processes understand it. 
There is no requirement that IPv4-mapped addressing is not disabled on a 
system supporting IPv6 (RFC4291 section 8 security considerations).

From RFC5156:


     2.2 <https://tools.ietf.org/html/rfc5156#section-2.2>. IPv4-Mapped
     Addresses



   ::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291 <https://tools.ietf.org/html/rfc4291>].  Addresses
   within this block should not appear on the public Internet.



You can put it in a AAAA record just as you can configure a 10.0.0.0/8 
address there, but there can be no expectation that it will do anything 
useful outside your own environment.

Regards,

Baldur