I hit the same error with the newest version core-2021.6.6. My SSD Disk 256GB was full that is how i found out. I got more than 500MB text files for a couple of hours. For me its not 3000 per 10 mins its like 200 000 for 10 mins. I dont have “default_config” , nmap , dhcp and currently im trying to figure out what is causing it.
I can see its the docker DNS
➜ log sudo docker ps | grep dns
60db8694e5dd ghcr.io/home-assistant/armv7-hassio-dns:2021.06.0 "/init" 4 hours ago Up 4 hours hassio_dns
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:60215 - 40549 "PTR IN 2.0.17.172.in-addr.arpa. udp 52 true 2048" NXDOMAIN qr,rd,ra 41 0.082305443s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 172.30.32.1:41332 - 22422 "PTR IN 107.1.168.192.in-addr.arpa. udp 55 true 2048" NXDOMAIN qr,rd,ra 44 6.242447876s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:33570 - 56066 "PTR IN 102.1.168.192.in-addr.arpa. udp 55 true 2048" NXDOMAIN qr,rd,ra 44 0.13718296s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 172.30.32.1:54249 - 40549 "PTR IN 2.0.17.172.in-addr.arpa. udp 52 true 2048" NXDOMAIN qr,rd,ra 41 6.37204171s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 172.30.32.1:40576 - 56066 "PTR IN 102.1.168.192.in-addr.arpa. udp 55 true 2048" NXDOMAIN qr,rd,ra 44 5.687066021s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:53884 - 56963 "PTR IN 2.1.168.192.in-addr.arpa. udp 53 true 2048" NOERROR - 0 12.843435775s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [ERROR] plugin/errors: 2 2.1.168.192.in-addr.arpa. PTR: tls: DialWithDialer timed out
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:51206 - 61188 "PTR IN 138.1.168.192.in-addr.arpa. udp 55 true 2048" NOERROR - 0 9.272147204s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [ERROR] plugin/errors: 2 138.1.168.192.in-addr.arpa. PTR: tls: DialWithDialer timed out
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:55640 - 42006 "PTR IN 101.1.168.192.in-addr.arpa. udp 55 true 2048" NOERROR - 0 9.228136978s
Jul 1 16:42:57 pi4 60db8694e5dd[756]: [ERROR] plugin/errors: 2 101.1.168.192.in-addr.arpa. PTR: tls: DialWithDialer timed out
Jul 1 16:42:58 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:56376 - 56963 "PTR IN 2.1.168.192.in-addr.arpa. udp 53 true 2048" NOERROR - 0 13.004465817s
Jul 1 16:42:58 pi4 60db8694e5dd[756]: [ERROR] plugin/errors: 2 2.1.168.192.in-addr.arpa. PTR: tls: DialWithDialer timed out
Jul 1 16:42:58 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:37551 - 56963 "PTR IN 2.1.168.192.in-addr.arpa. udp 53 true 2048" NXDOMAIN qr,rd,ra 42 4.965997912s
Jul 1 16:42:58 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:53369 - 38627 "PTR IN 106.1.168.192.in-addr.arpa. udp 55 true 2048" NXDOMAIN qr,rd,ra 44 4.966344368s
Jul 1 16:42:58 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:39277 - 22422 "PTR IN 107.1.168.192.in-addr.arpa. udp 55 true 2048" NXDOMAIN qr,rd,ra 44 4.966840212s
Jul 1 16:42:58 pi4 60db8694e5dd[756]: [INFO] 127.0.0.1:38663 - 5714 "PTR IN 205.1.168.192.in-addr.arpa. udp 55 true 2048" NXDOMAIN qr,rd,ra 44 4.968133615s
CoreDNS is using 100% CPU.
After ‘ha dns restart’ we are back to normal. but i’m trying to find out the root cause.