<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div>On Thu, 2021-05-13 at 20:55 -0500, Steven Garner via Pdns-users wrote:</div><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><div dir="ltr">Recently set up PowerDNS Authoritative Server (v 4.4.X) on 3 Ubuntu 20.04 LTS name servers using MySQL 8 replication as a backend. My master name server (<a href="http://ns1.opensourceserver.io">ns1.opensourceserver.io</a>) and one of the slaves (<a href="http://ns3.opensourceserver.io">ns3.opensourceserver.io</a>) are performing well, but the other slave (<a href="http://ns2.opensourceserver.io">ns2.opensourceserver.io</a>) cannot even be found.<br><br>I am wondering if it might be because of this unexpected result:<br><br><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><div><font face="monospace"># netstat -alnp4 | grep pdns<br></font><font face="monospace">tcp 0 0 <a href="http://0.0.0.0:53">0.0.0.0:53</a> 0.0.0.0:* LISTEN 53992/pdns_server<br></font><font face="monospace">tcp 0 0 <a href="http://127.0.0.1:59010">127.0.0.1:59010</a> <a href="http://127.0.0.1:3306">127.0.0.1:3306</a> ESTABLISHED 53992/pdns_server<br></font><font face="monospace">tcp 0 0 <a href="http://127.0.0.1:59008">127.0.0.1:59008</a> <a href="http://127.0.0.1:3306">127.0.0.1:3306</a> ESTABLISHED 53992/pdns_server<br></font><font face="monospace">tcp 0 0 <a href="http://127.0.0.1:59012">127.0.0.1:59012</a> <a href="http://127.0.0.1:3306">127.0.0.1:3306</a> ESTABLISHED 53992/pdns_server<br></font><font face="monospace">tcp 0 0 <a href="http://127.0.0.1:59014">127.0.0.1:59014</a> <a href="http://127.0.0.1:3306">127.0.0.1:3306</a> ESTABLISHED 53992/pdns_server<br></font><font face="monospace">udp 0 0 <a href="http://0.0.0.0:53">0.0.0.0:53</a> 0.0.0.0:* 53992/pdns_server</font></div><div><br></div></blockquote></div></blockquote><div><br></div><div><br></div><div>The 3306 connections are pdns-server connecting to MySQL.</div><div><br></div><div><br></div><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><div dir="ltr"><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><div><font face="monospace">dig <a href="http://opensourceserver.io">opensourceserver.io</a> @<a href="http://ns2.opensourceserver.io">ns2.opensourceserver.io</a></font><font face="monospace"><br></font><font face="monospace">; <<>> DiG 9.10.6 <<>> <a href="http://opensourceserver.io">opensourceserver.io</a> @<a href="http://ns2.opensourceserver.io">ns2.opensourceserver.io</a><br></font><font face="monospace">;; global options: +cmd<br></font><font face="monospace">;; connection timed out; no servers could be reached</font></div><div><br></div></blockquote></div></blockquote><div><br></div><div>Your server does actually seem to answer queries from outside ... over TCP. Not so much over UDP.</div><div><br></div><div><div><div><span style="font-family:monospace">19:36:00.599475 eth0 Out IP 10.75.105.10.52535 > 207.177.51.156.53: 62512+ [1au] A? ns2.opensourceserver.io. (64)
<br>19:36:00.678967 eth0 In IP 207.177.51.156 > 10.75.105.10: ICMP 207.177.51.156 udp port 53 unreachable, length 36<br></span></div></div></div><div><br></div><div>I get a port unreachable on UDP 53. ANY queries over TCP work, though:</div><div><br></div><div><div><span style="font-family:monospace">$ dig @207.177.51.156 any opensourceserver.io <br>
<br>; <<>> DiG 9.16.15 <<>> @207.177.51.156 any opensourceserver.io
<br>; (1 server found)
<br>;; global options: +cmd
<br>;; Got answer:
<br>;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12321
<br>;; flags: qr aa rd; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 4
<br>;; WARNING: recursion requested but not available
<br>
<br>;; OPT PSEUDOSECTION:
<br>; EDNS: version: 0, flags:; udp: 1232
<br>;; QUESTION SECTION:
<br>;opensourceserver.io. IN ANY
<br>
<br>;; ANSWER SECTION:
<br>opensourceserver.io. 120 IN A 76.76.238.10
<br><other answers chopped><br>
<br>;; Query time: 79 msec
<br>;; SERVER: 207.177.51.156#53(207.177.51.156)
<br>;; WHEN: Thu May 13 19:37:01 PDT 2021
<br>;; MSG SIZE rcvd: 366<br>
<br></span></div></div><div>Recheck your UDP forwarding and firewalls.</div><div><span></span></div></body></html>