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<div class="moz-cite-prefix">On 24/12/2019 02:25, Jackson Yap wrote:<br>
</div>
<blockquote type="cite"
cite="mid:9f92c3cae7fb0849dedea2d0ecf7ffd4@mail.gmail.com">
<p class="MsoNormal">We realised when we do a pdns_control notify
'*' , many axfrs cannot be transferred to our pdns slave. We
have about 500+ zones in total.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Only when we do specific domain notify like
pdns_control notify '<a href="http://example.com"
moz-do-not-send="true">example.com</a>’, it will work
properly.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">My question is, what settings could have
provided mass pdns notify from working properly?</p>
</blockquote>
<p>I'd suggest you try using tcpdump to look at what's happening.
Some thoughts:<br>
</p>
<p>1. Notifies are sent over UDP. Maybe when you try to send 500
UDP packets simultaneously, some of them are being thrown away
(e.g. some buffer is overflowing). tcpdump at the receiving
server(s) too if possible.<br>
</p>
<p>2. Maybe when there are too many incoming connections, some are
being rejected (look for R[ST] as the response). See <a
href="https://docs.powerdns.com/authoritative/settings.html#max-tcp-connections">https://docs.powerdns.com/authoritative/settings.html#max-tcp-connections</a></p>
<p>3. Maybe your backend database is slow and can't handle that many
concurrent AXFRs</p>
<p>As for solutions: maybe you're better avoiding doing pdns_control
notify "*". One way would be to spread your notifies over a
minute or two. Another would be to use native replication between
your backend databases, which avoids the need for AXFR completely.<br>
</p>
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