Some folks in the IPv6 WG may not be in IETF v6ops, and they could also contribute to this “measurement experiment”. Regards, Jordi @jordipalet

El 13 abr 2026, a las 11:52, jordi.palet@consulintel.es <jordi.palet=40consulintel.es@dmarc.ietf.org> escribió:

Hi all,

I’m wondering how much actual deployment of RFC7050/8880 is there and that means *having ipv4only.arpa zone* available in the resolvers of the operators.

With this small experiment, we can try to measure what is the situation, at last from the mobile operators being used by the participants.

Note that this experiment is only possible if your mobile operator is actually using 464XLAT (or even only NAT64, don’t think many do).

I got a confirmation from one big network operator about it, but I’m not sure that is the same in all the other deployments in mobile networks, so I wonder if each participant can provide their own experience or you already know for sure what is the actual deployment situation in your operator.

If you don’t know from first hand how your mobile operator is doing, or even knowing it, you want to verify, please use the following steps:

1) Connect a computer with has dig installed to the mobile network via tethering (the mobile device should be using the mobile network, of course).

2) Ensure that the DNS server(s) configuration is the default provided by the mobile operator (usually the mobile phones don’t allow changing it, but you may have changed it in the computer, so you need, for the test, to return it to DHCP, which means the mobile phone will act as a DNS-proxy by means of the CLAT.

3) Run and capture the results of: dig AAAA +cd ipv4only.arpa

4) If you don’t have dig, you can use nslookup (however it doesn’t allow clearing the CD flag, see explanation below): nslookup -q=AAAA ipv4only.arpa

There may be other ways to do this test, even directly from the mobile phone, but I found that the dnsutils available for mobiles don’t allow setting the CD (checking disabled) bit to 0. In that case, depending on the DNS64 server configuration may not perform DNS64 synthesis, so will not be able to reveal the actual Pref64. If the ipv4only.arpa is correctly configured, it will also reveal the correct Pref64 even failing to set to 0 the CD.

You can actually run the test with some dnsutil in the phone, then in the computer, so we can confirm differences.

Please, to avoid extra noise in the list, reply directly to me (jordi.palet@theipv6company.com <mailto:jordi.palet@theipv6company.com>), and I will make a summary to the list in a few days.

You need to confirm to me the mobile operator and country, if you’re using Android or iOS, what version and details about how you did the test, in addition to to the dig or nslookup results. Better if you are able to do the test both, in the mobile and the computer.

Tks a lot in advance !

Regards, Jordi

@jordipalet

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