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<div class="moz-cite-prefix">On 23/05/2022 15.48, Thomas, Matthew
via dns-operations wrote:<br>
</div>
<blockquote type="cite"
cite="mid:mailman.221.1653313702.26837.dns-operations@lists.dns-oarc.net">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Arial",sans-serif;color:black">Configuration
1: Generate a synthetic NXDOMAIN response to all queries with
no SOA provided in the authority section.</span><span
style="font-size:11.0pt"><o:p></o:p></span></p>
</blockquote>
<p>I believe the protocol says not to cache such answers at all.
Some implementations chose to cache at least a few seconds, but I
don't think all of them. Breaking caching seems risky to me, as
traffic could increase very much (if the TLD was queried a lot).<br>
</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:mailman.221.1653313702.26837.dns-operations@lists.dns-oarc.net"><span
style="font-size:11.0pt;font-family:"Arial",sans-serif;color:black">
</span><span style="font-size:11.0pt"><o:p></o:p></span>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Arial",sans-serif;color:black">Configuration
2: Generate a synthetic NXDOMAIN response to all queries with
a SOA record. Some example queries for the TLD .foo are
below:</span></p>
</blockquote>
<p>It still feels a bit risky to answer in this non-conforming way,
and I can't really see why attempt that. At apex the NXDOMAIN
would deny the SOA included in the very same answer...<br>
</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:mailman.221.1653313702.26837.dns-operations@lists.dns-oarc.net">
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Arial",sans-serif;color:black">Configuration
3: Use a properly configured empty zone with correct NS and
SOA records. Queries for the single label TLD would return a
NOERROR and NODATA response.</span><span
style="font-size:11.0pt"><o:p></o:p></span></p>
</blockquote>
<p>I expect that's OK, especially if it's a TLD that's seriously
considered. I'd hope that "bad" usage is mainly sensitive to
existence of records of other types like A.</p>
<p><br>
</p>
<p>--Vladimir | knot-resolver.cz<br>
</p>
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