IPv4-Mapped IPv6 Address used in DNS with AAAA-records

[Erik Nygren]

Dan Wing has been tracking these for years.  You can see the current set
and history of these going back to 2009:
https://www.employees.org/~dwing/aaaa-stats/

Current set from Alexa top-N is
https://www.employees.org/~dwing/aaaa-stats/ipv6-map.2023-07-29_0800.txt
contains mostly this case right now, but also a few others from opendns.com:

> bam-cell.cell.nr-data.net      has IPv4  has IPv6  ::ffff:162.247.243.30  (errno=22) (time=0.000037)bam-cell.nr-data.net           has IPv4  has IPv6  ::ffff:162.247.243.30  (errno=22) (time=0.000005)bam.cell.nr-data.net           has IPv4  has IPv6  ::ffff:162.247.243.29  (errno=22) (time=0.000007)bam.eu01.nr-data.net           has IPv4  has IPv6  ::ffff:185.221.87.23  (errno=22) (time=0.000003)bam.nr-data.net                has IPv4  has IPv6  ::ffff:162.247.243.29  (errno=22) (time=0.000006)block.opendns.com              has IPv4  has IPv6  ::ffff:208.67.219.157  (errno=22) (time=0.000003)bpb.opendns.com                has IPv4  has IPv6  ::ffff:208.67.219.158  (errno=22) (time=0.000006)fastly-mobile-collector.newrelic.com has IPv4  has IPv6  ::ffff:162.247.243.24  (errno=22) (time=0.000003)fastly-tls12-bam-cell.nr-data.net has IPv4  has IPv6  ::ffff:162.247.243.30  (errno=22) (time=0.000002)fastly-tls12-bam.nr-data.net   has IPv4  has IPv6  ::ffff:162.247.243.29  (errno=22) (time=0.000003)malware.opendns.com            has IPv4  has IPv6  ::ffff:208.67.219.152  (errno=22) (time=0.000004)
>
> As long as you have IPv4 on a client then most clients seem to just work.
Amusingly, curl will actually connect to this with "-6" but will just use
IPv4 (which might be a bug):

$ curl -v -6 bam-cell.nr-data.net
> *   Trying ::ffff:162.247.243.30:80...
> * TCP_NODELAY set
> * Connected to bam-cell.nr-data.net (::ffff:162.247.243.30) port 80 (#0)
> > GET / HTTP/1.1
> > Host: bam-cell.nr-data.net
> > User-Agent: curl/7.68.0
> [...]
>








On Fri, Jul 28, 2023 at 1:05 AM Thomas Schäfer <thomas at cis.uni-muenchen.de>
wrote:

> Hi,
>
> Thank you for answers so far.
> Since the support case is public and you may interested in bad
> entertainment (today is SysAdminDay)
>
> You can read it here:
>
>
> https://forum.newrelic.com/s/hubtopic/aAX8W0000015BUvWAM/bamnrdatanet-resolves-with-wrong-aaaarecords
>
> My today's highlight is:
>
> "We did this to drive down the cost with our DNS provider. Queries for
> AAAA records that didn't exist, followed by queries for A records, was
> costing us significantly and we needed to alleviate that."
>
> Just one comment to the players there:
>
> "new relic" is providing that service to Postbank/DeutscheBank (and
> probably more)
>
> ns1, the service with high costs for none existing AAAA-Records, is a
> IBM company.
>
> Big companies big mistakes....
>
> Have a nice weekend!
>
> Thomas
>
>
>
>
>
> --
>
> There’s no place like ::1
>
> Thomas Schäfer (Systemverwaltung)
> Ludwig-Maximilians-Universität
> Centrum für Informations- und Sprachverarbeitung
> Oettingenstraße 67 Raum C109
> 80538 München ☎ +49/89/2180-9706  ℻ +49/89/2180-9701
>
>
>
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