EX280 Troubleshooting And Diagnostics Practice Test 3 — 15 Questions

Question 1

An administrator needs to check the IP address and network status assigned to a running pod. Which command displays this information quickly?

Accepted Answer

oc get pod -o wide. oc get pod -o wide displays additional details including the pod IP address and the node it is scheduled on.

Answer

oc ip pod <pod-name>

Answer

oc describe pod <pod-name> --network

Answer

oc get network-attachment-definitions

Question 2

A pod is stuck in the 'ContainerCreating' state for an extended period. The administrator suspects a persistent volume mount timeout. Which resource events should they examine to confirm if the volume plugin is failing to attach the disk?

Accepted Answer

oc describe pvc <pvc-name>. Describing the persistent volume claim (PVC) or the pod itself displays storage attachment events from the attach/detach controller.

Answer

oc adm diagnostics storage

Answer

oc logs deployment/<deployment-name>

Answer

oc get pv -o json

Question 3

An administrator wants to view the last 50 lines of logs for a pod named 'api-server-xyz' and keep the stream open for new log entries. Which command should they use?

Accepted Answer

oc logs api-server-xyz --tail=50 -f. Combining --tail=50 and -f in the oc logs command shows the last 50 lines and then tails new log output.

Answer

oc describe pod api-server-xyz --lines=50

Answer

oc logs api-server-xyz --lines=50 --follow

Answer

oc tail api-server-xyz -n 50

Question 4

An administrator needs to troubleshoot an application that fails to resolve internal cluster service names. They decide to run an interactive shell inside a temporary debugging pod with DNS tools installed. Which command creates this diagnostic pod?

Accepted Answer

oc run net-debug --rm -it --image=quay.io/openshift/origin-cli:latest -- /bin/bash. oc run with --rm -it allows spinning up an ephemeral container (such as busybox) for interactive network troubleshooting.

Answer

oc debug service/my-svc

Answer

oc adm tcp-dump

Answer

oc rsh net-debug

Question 5

An administrator wants to check the resource requests and limits across all pods in a specific namespace. Which command provides this summary?

Accepted Answer

oc get pods -o custom-columns=NAME:.metadata.name,CPU:.spec.containers[*].resources.requests.cpu. oc adm top pod lists CPU and memory usage for pods, while describing or querying pod YAML specifications reveals requests and limits.

Answer

oc get quota

Answer

oc describe namespace my-namespace

Answer

oc adm top pod -n my-namespace

Question 6

An administrator notices that a node is marked as 'SchedulingDisabled' (Cordoned). Which command should be executed to allow pods to be scheduled on this node again?

Accepted Answer

oc adm uncordon <node-name>. oc adm uncordon marks a previously cordoned node as schedulable.

Answer

oc patch node <node-name> --type=json -p='[{"op": "replace", "path": "/spec/unschedulable", "value": false}]'

Answer

oc adm drain <node-name> --undo

Answer

oc scale node <node-name> --replicas=1

Question 7

The cluster monitoring stack is failing because Prometheus pods in the openshift-monitoring namespace are crashing due to disk space exhaustion on the Prometheus PersistentVolume. How can the administrator inspect the current disk usage inside the Prometheus container?

Accepted Answer

oc exec -n openshift-monitoring prometheus-k8s-0 -c prometheus -- df -h. Using oc exec to run df -h inside the Prometheus container allows checking mount point disk space utilization.

Answer

oc debug node/<node-name> -- df -h

Answer

oc logs -n openshift-monitoring deployment/prometheus-adapter

Answer

oc adm top volume

Question 8

An OpenShift cluster's Ingress controller is failing to route external traffic because the router pods are crashing with 'Bind: address already in use'. What is the most likely cause that an administrator should investigate?

Accepted Answer

Another service or daemon on the worker node is already binding to host ports 80 or 443.. HostPort or hostNetwork conflicts occur when multiple router replicas or daemonsets attempt to bind to ports 80 and 443 on the same worker node interface.

Answer

The OAuth client secret is invalid.

Answer

The default router deployment replica count is set to zero.

Answer

The wildcard DNS record for the cluster points to the wrong IP address.

Question 9

An application team reports that their application cannot connect to an external database due to a firewall blocking port 3306. The administrator wants to test network connectivity from inside a running application pod to the external database host. Which tool can they run using 'oc exec'?

Accepted Answer

oc exec <pod-name> -- nc -zv db.example.com 3306. Running nc (netcat), telnet, or curl inside the running container via oc exec tests TCP socket connectivity to external endpoints.

Answer

oc network test db.example.com 3306

Answer

oc adm port-forward pod/<pod-name> 3306:3306

Answer

oc debug pod/<pod-name> -- test-connection

Question 10

An administrator needs to list all persistent volume claims in the cluster that are currently stuck in the 'Pending' state. Which command can be combined with grep or custom formatting to identify them?

Accepted Answer

oc get pvc --all-namespaces. oc get pvc --all-namespaces lists all PVCs across the cluster, which can be inspected for their status.

Answer

oc describe storage-cluster

Answer

oc adm storage pending

Answer

oc get pv --status=Pending

Question 11

An OpenShift cluster administrator receives an alert that etcd disk fsync durations are excessively high. Which performance metric is the etcd diagnostic tool measuring when evaluating disk latency?

Accepted Answer

The time taken for etcd to commit WAL (Write-Ahead Log) entries to persistent storage via fsync.. etcd disk performance relies heavily on synchronous disk writes (fsync). High fsync duration indicates slow underlying storage block devices.

Answer

The network round trip time between etcd follower and leader nodes.

Answer

The time taken by the Kubernetes API server to serialize JSON objects.

Answer

The garbage collection duration of expired etcd keys.

Question 12

An administrator wants to check the logs of the Cluster Version Operator to see why an upgrade failed. In which namespace does the CVO run?

Accepted Answer

openshift-cluster-version. The Cluster Version Operator is deployed and runs in the openshift-cluster-version namespace.

Answer

openshift-operator-lifecycle-manager

Answer

openshift-config-operator

Answer

kube-system

Question 13

An administrator needs to drain a worker node safely for hardware maintenance, but some pods have local emptyDir storage that would be permanently deleted. Which flag must be added to the drain command to allow eviction of these pods?

Accepted Answer

--delete-emptydir-data. Pods with emptyDir volumes are protected by default during drains. The --delete-emptydir-data flag overrides this protection.

Answer

--allow-local-volumes

Answer

--ignore-daemonsets=false

Answer

--force-local-storage

Question 14

A worker node's root filesystem reaches 100% capacity due to accumulated container images and logs, causing the kubelet to enter an eviction state. After freeing up disk space on the node, the administrator notices the node status remains NotReady. What action is required to clear the kubelet's node pressure condition?

Accepted Answer

Restart the kubelet service on the affected node or reboot the node.. Once disk pressure is resolved and container images/logs are garbage-collected, restarting the kubelet service via systemctl restart kubelet inside an oc debug session or rebooting the node clears the disk pressure taint.

Answer

Run 'oc adm uncordon' on the node.

Answer

Delete and recreate the clusterversion resource.

Answer

Scale the machineconfigpool to zero and back.

Question 15

An administrator wants to check the detailed configuration and current status of a specific Route named 'my-app-route'. Which command provides this?

Accepted Answer

oc describe route my-app-route. oc describe route my-app-route displays route hostnames, TLS settings, service weights, and backend service targets.

Answer

oc get route my-app-route --status

Answer

oc show route my-app-route

Answer

oc adm route-status my-app-route