CoreDNS does only work sporadically

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Cluster information:

Kubernetes version:v1.12.1
Cloud being used: Exoscale
Installation method: via link
Host OS: Ubuntu 18.04
CNI and version:
CRI and version:
Hypervisor: KVM


I hope somebody can help me!
I started a Minikube instance with only one node to test the behavior of DNS in a Kubernetes Cluster, I used the example deployment (“hello-minikube”) from the installation guide, but i am unable to get a response from it when I use curl to querry it (" curl hello-minikube.default.svc.cluster.local") also if i am trying to use nslookup i get an error ("** server can’t find hello-minikube.default.svc.cluster.local: SERVFAIL").
I looked into the documentation for Debugging DNS, but here it gets strange, when I execute a nslookup inside the busybox pod I get the right IP-address for the example-service and the DNS-service, but when I try curl or wget I get an error.
Can somebody please help me, with the cause of this problem?