Different RPZ behavior for IDN domains between BIND 9.20.23 and 9.20.26

[Ondřej Surý]

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!

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> 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
> 
> 
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> 
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