Lately I have problem with Pods in k8s. I have 5 masters and 5 worker nodes, where I have 19 Pods. If I make, for example: ssh sonar.***.ru from worker - all is OK, but if this command is run from Pod, it fails, because of time out or a lot of time find connect. or it takes a lot of time to connect.

I have flannel, docker, kubelet and kube-proxy, kubernetes is 1.13. What other information can I provide to get help in resolving the issue ? It started about 2 weeks ago.

update:

$ cat /etc/resolv.conf 

nameserver 192.168.0.10
search bamboo-agents-prod.svc.cluster.local svc.cluster.local cluster.local raiffeisen.ru
options ndots:5 

$ nslookup sonar.raiffeisen.ru

Server: 10.243.4.15
Address: 10.243.4.15#53
Name: sonar.raiffeisen.ru
Address: 10.243.90.81

The error I get why trying to ssh:

ssh: Could not resolve hostname sonar.raiffeisen.ru: Name or service not known 

I cannot connect to it at all and also cannot connect to any other host from all my Pods, not only one! ping is working, but for first package I also wait some time.