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<p>I would suggest doing what forwarders do, joining multiple
queries into single upstream request. When the answer arrives,
send replies to all requestors of this common transaction. If you
cannot fix your server to handle the response right away and have
pre-computed answers, as is common for authoritative servers.<br>
</p>
<p>It is expected authoritative server does not have to do anything
serious per client. What is that resource intensive operation we
are talking about? Do you sign on the fly? Can you explain a
bigger picture? Maybe there is a design of the service, which
could be improved instead. Attempt to suppress a retry when the
server does not answer quickly enough is not correct way of
solving it IMO.</p>
<p>Regards,<br>
Petr<br>
</p>
<div class="moz-cite-prefix">On 6/26/23 03:05, Fred Morris wrote:<br>
</div>
<blockquote type="cite"
cite="mid:0c81e3cc-e838-1aac-2e9c-89e831d321ea@m3047.net">
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<p>I have an authoritative server which performs a resource
intensive operation to determine an answer; sometimes it takes
long enough that BIND asks again (and again!). Firing off
multiple attempts to determine the answer just digs the hole
deeper.</p>
<p>What's the best approach, assuming the same client asks
repeatedly:</p>
<ul>
<li>Discard later queries, answer the first one?</li>
<li>Discard earlier queries, answer the last one?</li>
<li>Send same the response (when we get it) in response to all
queries (I don't like this one)?</li>
</ul>
<p>And does anyone know can the recommended mitigation be presumed
to be the best option regardless of the recursive server (BIND,
Unbound, etc.)?<br>
</p>
<p>Thanks in advance...</p>
<p>--</p>
<p>Fred Morris</p>
<p><br>
</p>
<br>
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<pre class="moz-signature" cols="72">--
Petr Menšík
Software Engineer, RHEL
Red Hat, <a class="moz-txt-link-freetext" href="https://www.redhat.com/">https://www.redhat.com/</a>
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB</pre>
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