Re: DNSSEC + Split DNS

Brian Candler via Pdns-users <[email protected]> Thu, 9 Apr 2026 10:09:11 +0100
Newsgroups gmane.network.dns.powerdns.user
Message-ID <[email protected]>
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On 09/04/2026 09:57, rob777 via Pdns-users wrote:
> The headache comes indeed mainly with this few shadow records - tough 
> i'm not sure if i mean exactly the same as you with the term "Shadow 
> Record".
>
> Example what i mean:
>
> External Side:
> - a configured A Record server01.bla.test.com 
> <http://server01.bla.test.com> points to 194.88.45.32 on the external 
> Public Zone of test.com <http://test.com> in the AWS R53 config
> - only external clients are resolving server01.bla.test.com 
> <http://server01.bla.test.com> to this 194.88.145.32 IP
>
>
> Internal Side:
> - a configured A Record server01.bla.test.com 
> <http://server01.bla.test.com> points to 192.168.1.22 on the internal 
> bla.test.com <http://bla.test.com> Zone on the internal Powerdns 
> Authoritative
> - only internal Clients/Servers resolve server01.bla.test.com 
> <http://server01.bla.test.com> to this 192.168.1.22 IP via the 
> forward-zone=bla.test.com <http://bla.test.com> on the internal DNS 
> Recursor
>
Ah, so these subdomains are also visible to public clients, not purely 
for internal consumption? And you're going to sign these subdomains?

To get internal clients to see a different result for 
server01.bla.test.com than what is in the public DNS, configuring a 
Response Policy Zone on the recursor is the way I'd do it. This is what 
RPZ is designed for: to override specific DNS answers.

However, I believe it should also work to have a different, 
internal-only (and unsigned) bla.test.com zone with forward-zones and 
NTA for bla.test.com on the recursor.

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    <div class="moz-cite-prefix">On 09/04/2026 09:57, rob777 via
      Pdns-users wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAAPVCxwb30k9bPcbPUDqbjxdHvvzvc4chZ_9v1Ssmeeeh1HUQw@mail.gmail.com">
      <div>The headache comes indeed mainly with this few shadow records
        - tough i'm not sure if i mean exactly the same as you with the
        term "Shadow Record".</div>
      <div><br>
      </div>
      <div>Example what i mean:<br>
        <br>
      </div>
      <div>External Side:</div>
      <div>- a configured A Record <a
          href="http://server01.bla.test.com" moz-do-not-send="true">server01.bla.test.com</a>
        points to 194.88.45.32 on the external Public Zone of <a
          href="http://test.com" moz-do-not-send="true">test.com</a> in
        the AWS R53 config</div>
      <div>- only external clients are resolving <a
          href="http://server01.bla.test.com" moz-do-not-send="true">server01.bla.test.com</a>
        to this 194.88.145.32 IP</div>
      <div><br>
      </div>
      <div><br>
      </div>
      <div>Internal Side:<br>
      </div>
      <div>- a configured A Record <a
          href="http://server01.bla.test.com" moz-do-not-send="true">server01.bla.test.com</a>
        points to 192.168.1.22 on the internal <a
          href="http://bla.test.com" moz-do-not-send="true">bla.test.com</a>
        Zone on the internal Powerdns Authoritative</div>
      <div>- only internal Clients/Servers resolve <a
          href="http://server01.bla.test.com" moz-do-not-send="true">server01.bla.test.com</a>
        to this 192.168.1.22 IP via the forward-zone=<a
          href="http://bla.test.com" moz-do-not-send="true">bla.test.com</a>
        on the internal DNS Recursor</div>
      <div><br>
      </div>
    </blockquote>
    <p>Ah, so these subdomains are also visible to public clients, not
      purely for internal consumption? And you're going to sign these
      subdomains?</p>
    <p>To get internal clients to see a different result for
      server01.bla.test.com than what is in the public DNS, configuring
      a Response Policy Zone on the recursor is the way I'd do it. This
      is what RPZ is designed for: to override specific DNS answers.</p>
    <p>However, I believe it should also work to have a different,
      internal-only (and unsigned) bla.test.com zone with forward-zones
      and NTA for bla.test.com on the recursor.</p>
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