I have Cent-Os Linux based environment. Kubernetes is installed. I have connection issue between Kubernetes CoreDNS pod and my IBM DNS IPs.. CoreDNS logs shows it is getting timeout while resolving DNS IPs...

My Kubernetes CoreDNS Pod details

[root@master ~]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME                      READY   STATUS    RESTARTS   AGE
coredns-f9fd979d6-gp4mt   1/1     Running   0          134m
coredns-f9fd979d6-pbtzv   1/1     Running   0          134m
[root@master ~]#

I have check and verify that CoreDNS Service is Running and Listen.

[root@master ~]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME                      READY   STATUS    RESTARTS   AGE
coredns-f9fd979d6-gp4mt   1/1     Running   0          120m
coredns-f9fd979d6-pbtzv   1/1     Running   0          120m


[root@master ~]# kubectl exec -ti r4b1064f957-apim-v2-587c56d685-68slk -n connectapi -- nslookup kubernetes.default
;; connection timed out; no servers could be reached

command terminated with exit code 1
[root@master ~]#

rroot@master ~]# kubectl logs --namespace=kube-system -l k8s-app=kube-dns
[INFO] 127.0.0.1:59371 - 17727 "HINFO IN 8064230894866973346.7137657240395431905. udp 57 false 512" NOERROR - 0 2.000271291s
[ERROR] plugin/errors: 2 8064230894866973346.7137657240395431905. HINFO: read udp 192.168.89.65:45824->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:47446 - 44904 "HINFO IN 8064230894866973346.7137657240395431905. udp 57 false 512" NOERROR - 0 2.000474285s
[ERROR] plugin/errors: 2 8064230894866973346.7137657240395431905. HINFO: read udp 192.168.89.65:53775->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:44669 - 36227 "HINFO IN 8064230894866973346.7137657240395431905. udp 57 false 512" NOERROR - 0 2.000324096s
[ERROR] plugin/errors: 2 8064230894866973346.7137657240395431905. HINFO: read udp 192.168.89.65:37766->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:51958 - 16638 "HINFO IN 8064230894866973346.7137657240395431905. udp 57 false 512" NOERROR - 0 2.000321582s
[ERROR] plugin/errors: 2 8064230894866973346.7137657240395431905. HINFO: read udp 192.168.89.65:46660->10.0.80.12:53: i/o timeout
[INFO] 127.0.0.1:36848 - 16704 "HINFO IN 8064230894866973346.7137657240395431905. udp 57 false 512" NOERROR - 0 2.000349667s
[ERROR] plugin/errors: 2 8064230894866973346.7137657240395431905. HINFO: read udp 192.168.89.65:44920->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:57561 - 32677 "HINFO IN 8281118932564903114.5852514894723417063. udp 57 false 512" NOERROR - 0 2.00047641s
[ERROR] plugin/errors: 2 8281118932564903114.5852514894723417063. HINFO: read udp 192.168.89.66:36894->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:42113 - 48703 "HINFO IN 8281118932564903114.5852514894723417063. udp 57 false 512" NOERROR - 0 2.000318123s
[ERROR] plugin/errors: 2 8281118932564903114.5852514894723417063. HINFO: read udp 192.168.89.66:55750->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:55257 - 13768 "HINFO IN 8281118932564903114.5852514894723417063. udp 57 false 512" NOERROR - 0 2.000417758s
[ERROR] plugin/errors: 2 8281118932564903114.5852514894723417063. HINFO: read udp 192.168.89.66:48968->10.0.80.11:53: i/o timeout
[INFO] 127.0.0.1:50237 - 5611 "HINFO IN 8281118932564903114.5852514894723417063. udp 57 false 512" NOERROR - 0 2.000282567s
[ERROR] plugin/errors: 2 8281118932564903114.5852514894723417063. HINFO: read udp 192.168.89.66:49009->10.0.80.12:53: i/o timeout
[INFO] 127.0.0.1:44747 - 29657 "HINFO IN 8281118932564903114.5852514894723417063. udp 57 false 512" NOERROR - 0 2.000321751s
[ERROR] plugin/errors: 2 8281118932564903114.5852514894723417063. HINFO: read udp 192.168.89.66:37877->10.0.80.11:53: i/o timeout

Can you please suggest why Kubernetes Coredns is not communicating with IBM DNS IPs. Why it is getting timeout while trying to connect to DNS...