Services & Networking

A pod is running with the default DNS policy. The cluster DNS service is at 10.96.0.10. The node's /etc/resolv.conf has nameserver 8.8.8.8. When the pod tries to resolve an external hostname like 'example.com', which DNS server will it query first?

A Kubernetes cluster has a Service named 'web-svc' of type ClusterIP in the 'production' namespace. The Service selects pods with label 'app=web'. A NetworkPolicy in the same namespace is applied with the following spec: ```yaml apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-web spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - podSelector: matchLabels: role: frontend ``` A pod with label 'role=frontend' in the 'staging' namespace attempts to connect to 'web-svc.production.svc.cluster.local' on port 80. What is the result?

A Kubernetes cluster uses Calico as the CNI plugin. Two pods on different nodes cannot communicate, but pods on the same node can. Network policies are not enforced. What is the most likely cause?

An administrator notices that traffic to a Service is not being forwarded to any pod. The Service has selector 'app: web' and there are pods with that label. However, 'kubectl get endpoints' shows no endpoints. What is the most likely cause?

You are tasked with troubleshooting a web application that is deployed in a Kubernetes cluster. The application consists of a Deployment named 'web-app' with 3 replicas, each running a container that listens on port 3000. A Service named 'web-service' of type ClusterIP with selector 'app: web' and port 80 targeting port 3000 has been created. Additionally, an Ingress resource named 'web-ingress' is configured with a host rule for 'example.com' and backend service 'web-service' on port 80. Users report that accessing http://example.com results in a 503 Service Unavailable error. You verify that all pods are running, but kubectl get pods shows the READY column as 0/1 for each pod. The Ingress controller logs show 'upstream connect error or disconnect/reset before headers'. You check the endpoints: 'kubectl get endpoints web-service' shows no endpoints. The pods have the label 'app: web'. What should you do to resolve the issue?

A company deploys a web application with multiple replicas in a Kubernetes cluster. Users report intermittent connectivity issues. The application pods are exposed via a ClusterIP Service. To ensure stable connectivity, which action should be taken?

A cluster has multiple namespaces: 'frontend', 'backend', and 'monitoring'. A pod in the 'frontend' namespace needs to reach a Service named 'db-service' in the 'backend' namespace. The 'db-service' Service is of type ClusterIP. Which DNS name should the pod use?

Which TWO of the following are valid reasons to use a Headless Service?

A Kubernetes cluster uses kube-proxy in IPVS mode. A Service named 'api-svc' of type ClusterIP has three endpoints: 10.244.1.5:8080, 10.244.2.6:8080, and 10.244.3.7:8080. A client pod repeatedly connects to 'api-svc' and observes that all connections are routed to the same endpoint, 10.244.1.5:8080. The client pod and the endpoints are on different nodes. What is the most likely cause?

A company wants to expose a web application running as a Deployment with 3 replicas to external users. They need a stable IP address that does not change and the ability to terminate TLS. Which resource should they use?

Given the following YAML manifests in the same namespace: ```yaml apiVersion: v1 kind: Pod metadata: name: my-pod labels: app: my-app spec: containers: - name: app image: nginx ports: - containerPort: 8080 --- apiVersion: v1 kind: Service metadata: name: my-service spec: selector: app: my-app ports: - port: 80 targetPort: 8080 ``` A pod in the same namespace tries to reach my-service on port 80. What is the most likely outcome?