Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (OpenShift Container Platform 4.9.5 bug fix update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2021:4005
Verified it with 4.9.0-0.nightly-2021-10-25-215312 on IPI on OpenStack and passed. % oc get clusterversion NAME VERSION AVAILABLE PROGRESSING SINCE STATUS version 4.9.0-0.nightly-2021-10-25-215312 True False 3h13m Cluster version is 4.9.0-0.nightly-2021-10-25-215312 % 2. check bufsize in all the nodes, which is 512 as expected. % oc debug node/hongli-osp-77mqb-worker-0-4wb68 Starting pod/hongli-osp-77mqb-worker-0-4wb68-debug ... To use host binaries, run `chroot /host` Pod IP: 192.168.1.64 If you don't see a command prompt, try pressing enter. sh-4.4# chroot /host sh-4.4# cat /etc/coredns/Corefile . { errors bufsize 512 health :18080 forward . 10.11.142.1 { policy sequential } cache 30 reload ... <-----snip-----> sh-4.4# % 3. Can carry out dns query of github.com successfully in another pod % oc rsh centos-pod sh-4.4# dig github.com ; <<>> DiG 9.11.13-RedHat-9.11.13-6.el8_2.1 <<>> github.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43009 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ; COOKIE: 26b11204064b3a73 (echoed) ;; QUESTION SECTION: ;github.com. IN A ;; ANSWER SECTION: github.com. 30 IN A 140.82.114.3 ;; Query time: 6 msec ;; SERVER: 172.30.0.10#53(172.30.0.10) ;; WHEN: Tue Oct 26 07:30:37 UTC 2021 ;; MSG SIZE rcvd: 77 sh-4.4# 4. check the log from coredns-hongli-osp-77mqb-master-0 % oc -n openshift-openstack-infra logs coredns-hongli-osp-77mqb-master-0 -c coredns .:53 .:53 [INFO] plugin/reload: Running configuration MD5 = 87d5bf283029acbfab5b6ea67554f3d7 CoreDNS-1.8.4 linux/amd64, go1.16.6, [INFO] Reloading [INFO] plugin/reload: Running configuration MD5 = 8227ce1dd8a14df0a611e511fdce7c7f [INFO] Reloading complete [INFO] Reloading [INFO] plugin/reload: Running configuration MD5 = b799517340ad05793b84d6dd28800c31 [INFO] Reloading complete [INFO] Reloading [INFO] plugin/reload: Running configuration MD5 = 7bfbc4c20f6d73534fa654d90a7e3ca1 [INFO] Reloading complete [INFO] Reloading [INFO] plugin/reload: Running configuration MD5 = d0c953b676d0e1209574da31aef5f242 [INFO] Reloading complete [INFO] Reloading [INFO] plugin/reload: Running configuration MD5 = fc41c39ccf71c12a8d7e5d0621be910b [INFO] Reloading complete [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:48367->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:40662->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:32876->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:49915->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:38792->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:47832->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:59467->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:56014->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:44346->10.11.142.1:53: i/o timeout [ERROR] plugin/errors: 2 github.com. A: read udp 192.168.3.226:57664->10.11.142.1:53: i/o timeout zsh: command not found: .:53 %