Kubernetes pods dns issue with kube-flannel.

kubectl -n kube-system logs coredns-6fdfb45d56-2rsxc


.:53
[INFO] plugin/reload: Running configuration MD5 = 8b19e11d5b2a72fb8e63383b064116a1
CoreDNS-1.6.7
linux/amd64, go1.13.6, da7f65b
[ERROR] plugin/errors: 2 1898610492461102613.3835327825105568521. HINFO: read udp 10.244.2.28:59204->192.168.0.115:53: i/o timeout
[ERROR] plugin/errors: 2 1898610492461102613.3835327825105568521. HINFO: read udp 10.244.2.28:51845->192.168.0.116:53: i/o timeout
[ERROR] plugin/errors: 2 1898610492461102613.3835327825105568521. HINFO: read udp 10.244.2.28:49404->192.168.0.115:53: i/o timeout

Debugging DNS Resolution

kubectl exec -ti dnsutils -- nslookup kubernetes.default
Server:    10.0.0.10
Address 1: 10.0.0.10

nslookup: can't resolve 'kubernetes.default'

How to Solve it ?

iptables -P FORWARD ACCEPT
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
sudo update-alternatives --set iptables /usr/sbin/iptables-legacy
systemctl restart docker
systemctl restart kubelet

Apply in Nodes/Master. And check if logs working or not.