@kodekloud: K8s Networking: Mastering the dnsPolicy Pitfall! Every Kubernetes pod uses /etc/resolv.conf to route domain lookups. In a standard setup, the nameserver points directly to CoreDNS, utilizing search paths like svc.cluster.local to resolve short names. However, if a pod's dnsPolicy misconfigures this file, internal cluster routing breaks completely while external internet access remains perfectly fine. This breakdown typically happens due to three primary policies. ClusterFirst is the standard that queries CoreDNS. Changing this to Default forces the pod to inherit the host node's DNS instead, blinding it to internal service records like kubernetes.default. Furthermore, pods using hostNetwork: true will completely bypass CoreDNS unless you explicitly assign them the ClusterFirstWithHostNet policy. If a container resolves google.com but fails on internal services, check its /etc/resolv.conf nameserver and pod specification. Applying the correct policy to your host-networked daemons or ingress controllers instantly restores cluster-wide service discovery. #Kubernetes #K8s #Networking #dnsPolicy #CoreDNS #DevOps #SRE #Troubleshooting #SysAdmin #CloudNative #PlatformEngineering #TechTips #Backend
