CKA Troubleshooting Practice Test 18 — 15 Questions

Question 1

You attempt to schedule a pod but it remains 'Pending'. 'kubectl describe pod' shows the event: '0/3 nodes are available: 3 node(s) didn't match node selector.' What is the MOST likely cause?

Accepted Answer

The pod's nodeSelector does not match any node labels. The event '0/3 nodes are available: 3 node(s) didn't match node selector' explicitly indicates that the pod's nodeSelector field specifies labels that no node in the cluster possesses. The scheduler filters nodes based on the nodeSelector, and since none match, the pod remains Pending. The fix is to either label a node to match the selector or correct the pod's nodeSelector.

Answer

A PersistentVolumeClaim is not bound

Answer

All nodes have insufficient memory or CPU

Answer

The nodes have taints that the pod does not tolerate

Question 2

A pod is in 'ImagePullBackOff' state. Which of the following is NOT a common cause?

Accepted Answer

The container requires more memory than the limit allows. ImagePullBackOff means the kubelet repeatedly failed to pull the container image and is backing off before retrying. Memory limits are enforced at container runtime after the image is pulled and the container starts, so an insufficient memory limit would cause OOMKilled or scheduling failures — not an image pull error. Therefore, 'requires more memory than the limit allows' is NOT a common cause of ImagePullBackOff.

Answer

The image registry requires authentication and no imagePullSecrets are configured

Answer

The image tag does not exist

Answer

The image name is misspelled

Question 3

You need to check the logs of a kubelet on a node. Which command should you run on the node?

Accepted Answer

journalctl -u kubelet. The kubelet is a systemd-managed service on most Kubernetes nodes (installed as kubelet.service), so its logs are captured by the systemd journal. Running `journalctl -u kubelet` queries the journal for entries tagged with the kubelet unit, showing startup messages, pod sync errors, certificate issues, and container runtime interactions. This is the canonical way to inspect kubelet behavior on a node for CKA troubleshooting tasks.

Answer

journalctl -u docker

Answer

dmesg

Answer

tail -f /var/log/apache2/access.log

Question 4

You run 'kubectl get pods' and see that a pod is in 'CrashLoopBackOff'. You want to examine the container's previous exit code. Which command provides this information?

Accepted Answer

kubectl describe pod pod-name. The correct option is B, `kubectl describe pod pod-name`, because the pod's status section in the describe output includes the container's `Last State` with the previous termination reason and exit code, which is exactly what is needed to examine why the container exited. `kubectl get events` (A) only shows cluster event messages and does not report the container's exit code. `kubectl logs pod-name --previous` (C) retrieves the previous container's log output, not its exit code, and `kubectl logs pod-name` (D) shows the current container's logs, which may be empty or unavailable in a CrashLoopBackOff state.

Answer

kubectl get events

Answer

kubectl logs pod-name --previous

Answer

kubectl logs pod-name

Question 5

You have a pod that is in 'Pending' state because it requires a PersistentVolumeClaim that is not bound. Which event would you see in 'kubectl describe pod'?

Accepted Answer

0/1 nodes are available: 1 pod has unbound immediate PersistentVolumeClaims. When a pod is in 'Pending' state due to an unbound PersistentVolumeClaim (PVC), the scheduler cannot place the pod until the PVC is bound to a PersistentVolume (PV). The event message '0/1 nodes are available: 1 pod has unbound immediate PersistentVolumeClaims' is generated by the Kubernetes scheduler when it evaluates the pod's PVC requirement and finds no matching PV that satisfies the claim's storage class, access modes, and size, causing the pod to remain unscheduled.

Answer

0/1 nodes are available: 1 node(s) didn't match node selector

Answer

Failed to pull image "myimage:latest"

Answer

0/1 nodes are available: 1 Insufficient memory

Question 6

A pod is in 'Pending' state. Which TWO of the following are possible causes? (Select 2)

Accepted Answer

Node has insufficient CPU or memory resources. Option A is correct because when a node lacks sufficient allocatable CPU or memory, the kube-scheduler cannot find a feasible node and leaves the pod in Pending with a FailedScheduling event. Option C is correct because a pod that references a PersistentVolumeClaim that is not yet Bound (for example, waiting on a dynamic provisioner or a matching PersistentVolume) will remain Pending until the PVC binds. Option B is incorrect because a non-zero container exit code indicates a runtime failure after the container started, producing CrashLoopBackOff or Error, not Pending. Option D is incorrect because OOMKilled occurs when a running container exceeds its memory limit, resulting in a terminated container rather than a Pending pod. Option E is incorrect because a misspelled image name causes an ImagePullBackOff/ErrImagePull status once the kubelet attempts to pull the image, not a Pending phase.

Answer

Container exited with non-zero exit code

Answer

Container was killed due to OOM

Answer

Image name is misspelled

Question 7

You are troubleshooting a scenario where a pod cannot communicate with another pod in the same namespace via service name. Which THREE steps would you take to diagnose the issue? (Select 3)

Accepted Answer

Run 'kubectl get endpoints' to verify the service has healthy endpoints. Options B, C, and E are correct. Checking endpoints (B) verifies the service has healthy pods. Exec into the pod and using curl (C) tests connectivity to the service's cluster IP. Exec into the pod and running nslookup (E) checks DNS resolution of the service name. Option A checks node status, which is not directly related to pod-to-pod communication via service name. Option D checks logs of the target pod, which may not reveal network issues.

Answer

Run 'kubectl get nodes' to check node status

Answer

Run 'kubectl logs' on the target pod to check application logs

Question 8

A pod is stuck in Pending state. Running 'kubectl describe pod mypod' reveals the event '0/4 nodes are available: 3 Insufficient memory, 1 node(s) had taints that the pod didn't tolerate'. What is the most likely cause?

Accepted Answer

The pod requests more memory than available on any node and does not tolerate a node taint. The pod is pending because no node can satisfy its resource requirements or tolerate the node taints. The event indicates insufficient memory and a taint issue. The correct answer is that the pod requests more memory than any node can allocate and also does not tolerate a node taint.

Answer

The kubelet on all nodes is not running

Answer

The pod's container image is not pullable

Answer

The pod is using a hostPort that conflicts with an existing pod

Question 9

You suspect the kubelet on a worker node has stopped. Which two commands should you run to confirm the kubelet status and check its logs?

Accepted Answer

systemctl status kubelet and journalctl -u kubelet. To check if the kubelet is running, use 'systemctl status kubelet'. To view logs, use 'journalctl -u kubelet'. The other options target the wrong service or are not applicable.

Answer

systemctl status docker and tail -f /var/log/syslog

Answer

kubectl get nodes and kubectl describe node <node>

Answer

systemctl restart kubelet and journalctl -u containerd

Question 10

To view the logs of a specific container in a multi-container pod named 'web-pod', which command is correct?

Accepted Answer

kubectl logs web-pod --container app-container. The correct command is 'kubectl logs web-pod -c app-container'. The -c flag specifies the container name.

Answer

kubectl logs web-pod --all-containers

Answer

kubectl logs app-container -p web-pod

Answer

kubectl logs -c web-pod app-container

Question 11

Which command shows resource usage for pods and nodes in the cluster?

Accepted Answer

kubectl top pods and kubectl top nodes. The metrics server must be installed. 'kubectl top pods' shows pod CPU/memory usage, and 'kubectl top nodes' shows node usage.

Answer

kubectl cluster-info

Answer

kubectl get --sort-by=.status.capacity

Answer

kubectl describe pods and kubectl describe nodes

Question 12

A pod is in ImagePullBackOff state. You run 'kubectl describe pod mypod' and see 'Failed to pull image "myapp:latest": rpc error: code = Unknown desc = Error response from daemon: manifest for myapp:latest not found: manifest unknown'. What is the most likely cause?

Accepted Answer

The image tag does not exist in the registry. The error indicates the image tag 'latest' does not exist in the registry. The tag may have been deleted or never pushed.

Answer

The node has insufficient disk space

Answer

The image is too large and exceeds the node's disk quota

Answer

The container registry requires authentication

Question 13

You have a Deployment with livenessProbe configured. The pod restarts every few minutes. 'kubectl describe pod' shows the liveness probe is failing with 'HTTP probe failed with statuscode: 503'. The application's /healthz endpoint returns 200 from within the pod using 'kubectl exec'. What could be the issue?

Accepted Answer

The livenessProbe is configured with the wrong port. The liveness probe is failing externally but the endpoint works internally. This suggests the probe is hitting the wrong port or the network path is different. The most likely cause is that the livenessProbe is configured with a wrong port number.

Answer

The readinessProbe is interfering with the livenessProbe

Answer

The application has a memory leak

Answer

The kubelet on the node is misconfigured

Question 14

You are unable to resolve a Service DNS name from within a pod. To test DNS resolution, which command should you run inside the pod?

Accepted Answer

kubectl exec -- nslookup . The correct command is 'kubectl exec -- nslookup '. nslookup or dig are common DNS troubleshooting tools.

Answer

kubectl describe svc <service-name>

Answer

kubectl logs <pod>

Answer

kubectl attach <pod>

Question 15

Which command lists all events in the cluster sorted by timestamp?

Accepted Answer

kubectl get events --sort-by=.metadata.creationTimestamp. 'kubectl get events --sort-by=.metadata.creationTimestamp' shows events sorted by creation time. Alternatively, 'kubectl get events -w' watches events but does not sort.

Answer

kubectl get events --watch

Answer

kubectl logs --events

Answer

kubectl describe events