[dns-operations] geo9/geo10.t-mobile.com Returning NXDOMAIN for WiFi Calling

[Crist Clark]

QNAME minimization. Their non-compliant load balancers pretending to be
authoritative servers give responses that break QNAME minimization.


On Tue, Nov 18, 2025 at 8:06 PM Richard Laager via dns-operations <
dns-operations at dns-oarc.net> wrote:

>
>
>
> ---------- Forwarded message ----------
> From: Richard Laager <rlaager at wiktel.com>
> To: dns-operations at lists.dns-oarc.net
> Cc:
> Bcc:
> Date: Tue, 18 Nov 2025 21:55:06 -0600
> Subject: geo9/geo10.t-mobile.com Returning NXDOMAIN for WiFi Calling
>
> Anyone have a good contact for T-Mobile authoritative DNS? I've had no
> response from dnsadmin at t-mobile.com.
>
> My customers are reporting that T-Mobile WiFi calling (sometimes) does not
> work on our Internet service. This appears to be due to DNS resolution
> failures.
>
> The cause of the failures seems to be that geo9.t-mobile.com and
> geo10.t-mobile.com incorrectly return NXDOMAIN when queried for NS
> records for epdg.epc.geo.mnc260.mcc310.pub.3gppnetwork.org and
> epc.geo.mnc260.mcc310.pub.3gppnetwork.org. Note that they correctly
> return an answer when queried for A records. See also:
> https://dnsviz.net/d/epdg.epc.mnc260.mcc310.pub.3gppnetwork.org/dnssec/
>
> --
> Richard
>
>
>
>
> ---------- Forwarded message ----------
> From: Richard Laager via dns-operations <dns-operations at dns-oarc.net>
> To: dns-operations at lists.dns-oarc.net
> Cc:
> Bcc:
> Date: Tue, 18 Nov 2025 21:55:06 -0600
> Subject: [dns-operations] geo9/geo10.t-mobile.com Returning NXDOMAIN for
> WiFi Calling
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