Hello all, Long time lurker on the message list and would like some performance and/or tuning advice. We've been using pdns-recursor as internal recursive nameservers for quite some time now. The original implementer of pdns departed and I was recently tasked with replacing or upgrading all of the servers with newer RHEL9 versions. I opted to build fresh and migrate the configuration to the latest 5.2 release.
I'm hearing occasional complaints about odd issues and/or clients cycling through their DNS servers rapidly (timeouts?). Manual testing DNS works but I am reading through the metrics and performance documentation. I am hoping someone with a more experienced eye could take a look at a sampling of the periodic statistics report (below) and provide some insight or prioritization on any urgent issues I should focus on studying first. My observations: * I do note that the performance documentation talks about firewalld/stateful firewalls impact but the legacy servers were using the same basic setup. If the firewall is the problem is there a way to validate this (other than stopping firewalld and waiting)? * The "worker" threads seem evenly distributed to my novice eye and our qps (queries per second) rate is low as I would expect since the name servers are internal only resources. * I ran a few pcaps and rec_control trace-regex for specific domain items being reported as problematic. Everything seemed to be working with the trace-regex always showing "Step3 Final resolve: No Error/6 or 8". Thank you in advance for your time and consideration. Sincerely, Scotsie ``` Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Periodic statistics report" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" cache-entries="23666" negcache-entries="497" questions="6831695" record-cache-acquired="286931329" record-cache-contended="64414" record-cache-contended-perc="0.02" record-cache-hitratio-perc="0.87" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Periodic statistics report" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" packetcache-acquired="16887684" packetcache-contended="1019" packetcache-contended-perc="0.01" packetcache-entries="7112" packetcache-hitratio-perc="37.75" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Periodic statistics report" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" edns-entries="38" failed-host-entries="50" non-resolving-nameserver-entries="0" nsspeed-entries="968" saved-parent-ns-sets-entries="65" throttle-entries="8" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Periodic statistics report" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" concurrent-queries="1" dot-outqueries="0" idle-tcpout-connections="0" outgoing-timeouts="36594" outqueries="14668546" outqueries-per-query-perc="214.71" tcp-outqueries="3131" throttled-queries-perc="1.90" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Periodic statistics report" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" taskqueue-expired="0" taskqueue-pushed="540" taskqueue-size="0" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Queries handled by thread" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" count="3470098" thread="0" tname="worker" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Queries handled by thread" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.170" count="3360836" thread="1" tname="worker" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Queries handled by thread" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.171" count="764" thread="2" tname="tcpworker" Apr 17 16:07:28 nsrecdns01-1 pdns-recursor[1092]: msg="Periodic QPS report" subsystem="stats" level="0" prio="Info" tid="0" ts="1744920448.171" averagedOver="1800" qps="117" ```
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