Different RPZ behavior for IDN domains between BIND 9.20.23 and 9.20.26

[Crist Clark]

I’d put money on the fact that that domain is fundamentally broken with
CNAME at apex as having something to do with it.

The BIND instance having the problem wouldn’t also happen to be downstream
from another caching resolver?

On Sat, Jul 25, 2026 at 12:33 AM Ondřej Surý <ondrej at isc.org> wrote:

> Well, if
> xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c
> matches bad-domain1.example. then something is definitely wrong.
>
> If you are not willing to share the exact reproducer than there's little
> we can do to help you.
>
> Ondrej
> --
> Ondřej Surý (He/Him)
> ondrej at isc.org
>
> ADHD brain at work: I sometimes lose track of my inbox. Please feel free
> to send a gentle nudge if you're waiting on a reply!
>
> My working hours and your working hours may be different. Please do not
> feel obligated to reply outside your normal working hours.
>
> > On 25. 7. 2026, at 09:28, Sachchidanand Upadhyay <supadhyay at nkn.in>
> wrote:
> >
> > Hi Ondrej,
> >
> > Thank you for your response.
> >
> > Each listed domain in the RPZ is rewritten via a CNAME to a single
> policy domain, and that policy domain has an A record in its authoritative
> zone.
> >
> > For example:
> >
> > bad-domain1.example.    CNAME    policy.example.net.
> > bad-domain2.example.    CNAME    policy.example.net.
> > bad-domain3.example.    CNAME    policy.example.net.
> > bad-domain4.example.    CNAME    policy.example.net.
> >
> > and in the authoritative zone:
> >
> > policy.example.net.     A        <IP address>
> >
> >
> > The same RPZ ruleset works correctly on BIND 9.20.23, while BIND 9.20.26
> logs the rewrite failure for the same query.
> >
> > Regards,
> > Sachchidanand Upadhyay
> >
> >
> >
> >
> >
> >
> > From: Ondřej Surý <ondrej at isc.org>
> > To: "Sachchidanand Upadhyay"<supadhyay at nkn.in>
> > Cc: "bind-users"<bind-users at lists.isc.org>
> > Date: Fri, 24 Jul 2026 17:12:09 +0530
> > Subject: Re: Different RPZ behavior for IDN domains between BIND 9.20.23
> and 9.20.26
> >
> > What is the rule to trigger this? It is hard to debug without seeing the
> exact ruleset that’s being used.
> >
> > Ondrej
> > --
> > Ondřej Surý (He/Him)
> > ondrej at isc.org
> >
> > ADHD brain at work: I sometimes lose track of my inbox. Please feel free
> to send a gentle nudge if you're waiting on a reply!
> >
> > My working hours and your working hours may be different. Please do not
> feel obligated to reply outside your normal working hours.
> >
> > On 24. 7. 2026, at 13:04, Sachchidanand Upadhyay via bind-users <
> bind-users at lists.isc.org> wrote:
> >
> > Hello,
> >
> > I am observing different RPZ behavior for an IDN domain after upgrading
> from BIND 9.20.23 to 9.20.26 and would appreciate any guidance.
> >
> > Environment:
> >
> > BIND 9.20.23: Works as expected
> > BIND 9.20.26: Fails
> > The BIND configuration and RPZ configuration are identical on both
> versions.
> >
> > The queried domain is an IDN. The domain itself is not present in the
> RPZ, yet BIND 9.20.26 logs an "RPZ QNAME rewrite failed" message for the
> query, while the same query is resolved successfully on BIND 9.20.23 using
> the same configuration. Below are the logs
> >
> > 24-Jul-2026 15:37:16.288 query-errors: debug 3: client @0x7fd386c93800
> <client_IP>#41889
> (xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c):
> view internal: rpz QNAME rewrite
> xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c
> stop on qresult in rpz_rewrite(): failure
> > 24-Jul-2026 15:37:16.288 query-errors: info: client @0x7fd386c93800
> <client_IP>#41889
> (xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c):
> view internal: query failed (failure) for
> xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c/IN/A
> at query.c:7651
> > 24-Jul-2026 15:37:16.288 query-errors: debug 4: fetch completed for
> xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c/A
> in 0.042000: failure/deadlock found
> [domain:xn--i1bn6adp9emg4dcbcajdeflxp1gua1n7bt10abief.xn--11b7cb3a6a.xn--h2brj9c,referral:1,restart:2,qrysent:4,timeout:0,lame:0,quota:0,neterr:0,badresp:0,adberr:0,findfail:0,valfail:4]
> >
> > If anyone has encountered this issue before or is aware of a workaround
> or solution, I would be grateful for your suggestions.
> >
> > Regards,
> > Sachchidanand Upadhyay
> >
> >
> > --
> > Visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe
> from this list.
> >
> >
>
> --
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>
>
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