EX280 Cluster Installation And Management Practice Test 3 — 15 Questions

Question 1

An OpenShift 4.14 cluster administrator has installed an Operator from OperatorHub into a custom namespace using a Subscription. The administrator notices that the Operator pod is not being created. Upon checking the Subscription, the installation mode is set to AllNamespaces, but the Operator target namespace is restricted. Which Operator Lifecycle Manager (OLM) object should the administrator inspect to troubleshoot why the CSV (ClusterServiceVersion) is not installing?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Inspect the OperatorGroup in the target namespace to ensure its targetNamespaces match or support the Subscription scope.. The OperatorGroup defines the target namespaces that an Operator can watch and install into. When a Subscription uses AllNamespaces mode but the OperatorGroup restricts targetNamespaces, OLM cannot reconcile the CSV into the desired scope, so the Operator pod never gets created. Inspecting the OperatorGroup in the target namespace reveals the mismatch.

Answer

Check the MachineConfigPool for paused reconciliation flags.

Answer

Review the ClusterVersion resource status for pending updates.

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Inspect the KubeletConfig custom resource for validation errors.

Question 2

An administrator notices that a worker node is in a 'NotReady' state due to a storage failure. The administrator successfully replaces the underlying physical machine and wants to clear the old node object from the OpenShift 4.14 cluster. Which command should be used?

Accepted Answer

oc delete node worker-old. To remove a node object from an OpenShift cluster, the correct command is `oc delete node <node-name>`. This deletes the Node resource from the cluster, and if the node is managed by a MachineSet, the Machine object may also be deleted or replaced. In this scenario, the administrator has already replaced the physical machine, so deleting the old node object is appropriate.

Answer

oc adm cordon worker-old --purge

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oc patch machine worker-old --type=merge -p '{"spec":{"deleted":true}}'

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oc remove node-status worker-old

Question 3

What is the primary function of the Machine Config Operator (MCO) in OpenShift 4.14?

Accepted Answer

Managing operating system configurations, file system changes, and software updates for cluster nodes.. The Machine Config Operator (MCO) is a core OpenShift component that manages the operating system configuration and updates of cluster nodes. It uses MachineConfig objects to apply changes such as systemd units, files, and kernel arguments, and it orchestrates rolling updates to nodes via the Machine Config Daemon. This ensures nodes are configured consistently and updated safely.

Answer

Handling external DNS records and cluster ingress routing.

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Provisioning cloud provider virtual machines for cluster scaling.

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Managing container image registries and secure image signing.

Question 4

An administrator needs to configure custom container runtime parameters (such as the maximum pod log size or maximum number of processes per container) across all worker nodes in an OpenShift 4.14 cluster. Which custom resource should the administrator create?

Accepted Answer

ContainerRuntimeConfig. The ContainerRuntimeConfig custom resource is specifically designed to modify container runtime settings such as maximum pod log size (logSizeMax) and maximum processes per container (pidsLimit) on OpenShift 4.x worker nodes. It works by generating a MachineConfig that updates the CRI-O configuration on the targeted nodes. This resource is part of the Machine Config Operator's API and is the correct way to apply runtime-level tuning across a node pool. KubeletConfig, while also a node-level configuration, handles kubelet parameters like pod density and eviction thresholds, not container runtime settings.

Answer

MachineHealthCheck

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KubeletConfig

Answer

NodeNetworkConfigurationPolicy

Question 5

An administrator needs to ensure that if a worker node freezes or becomes unresponsive for more than 5 minutes, the cluster automatically remediates it by deleting and recreating the underlying virtual machine instance. Which OpenShift 4.14 feature should the administrator configure?

Accepted Answer

MachineHealthCheck. MachineHealthCheck (MHC) is the OpenShift 4.x feature that monitors node conditions and, when a node is unhealthy beyond a configured timeout, triggers remediation by deleting the Machine object so the Machine API Operator recreates the underlying VM. Configuring 'maxUnhealthy' and 'nodeStartupTimeout' plus a selector for worker nodes achieves the 5-minute freeze remediation described.

Answer

NodeAutoscaler

Answer

MachineConfigPool

Answer

ClusterAutoscaler

Question 6

An administrator is troubleshooting a failed cluster upgrade in OpenShift 4.14. The upgrade channel is set to 'stable-4.14', but the cluster refuses to update to the latest target version. The administrator runs 'oc get clusterversion' and notes that a specific ClusterOperator reports 'Degraded=True'. What is the recommended next step?

Accepted Answer

Describe or inspect the degraded ClusterOperator to identify the root cause and resolve its configuration or resource issues.. The Cluster Version Operator (CVO) blocks upgrades when any ClusterOperator reports Degraded=True because a degraded operator indicates an unhealthy cluster component that could cause the upgrade to fail or leave the cluster in an unstable state. The correct next step is to investigate the specific degraded operator using 'oc describe clusteroperator ' or 'oc get clusteroperator -o yaml' to identify the root cause, such as misconfiguration, missing resources, or failing pods. Once the underlying issue is resolved and the operator reports Available=True and Degraded=False, the upgrade can proceed normally. This aligns with OpenShift's design principle that upgrades should only occur on a healthy cluster.

Answer

Switch the upgrade channel to 'fast-4.14' to bypass the degraded check.

Answer

Delete the Cluster Version Operator deployment to force a reset of the upgrade state machine.

Answer

Force the upgrade by running 'oc adm upgrade --to=<version> --force-ignore-degraded'.

Question 7

An administrator wants to view the available recommended upgrade paths for an OpenShift 4.14 cluster from the command line. Which command should the administrator run?

Accepted Answer

oc adm upgrade. `oc adm upgrade` displays the current cluster version and the available recommended upgrade paths, including the next minor/major versions the cluster can move to. Running it without arguments shows the upgrade status and recommendations, making it the correct command to view upgrade paths from the CLI.

Answer

oc describe upgrade-channel

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oc get clusterversion --recommendations

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oc cluster-version check

Question 8

Which namespace houses the core Cluster Version Operator (CVO) in an OpenShift 4.14 cluster?

Accepted Answer

openshift-cluster-version. The Cluster Version Operator (CVO) runs in the openshift-cluster-version namespace, where it manages cluster updates by orchestrating the rollout of new versions. This namespace is dedicated to the CVO and its associated resources, such as the ClusterVersion object.

Answer

openshift-machine-api

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openshift-operator-lifecycle-manager

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openshift-config

Question 9

An administrator wants to check whether any worker nodes in an OpenShift 4.14 cluster are currently unschedulable (cordoned). Which command provides this information quickly?

Accepted Answer

oc get nodes. The `oc get nodes` command lists all nodes in the cluster along with their status, including a `SchedulingDisabled` flag that appears when a node is cordoned (unschedulable). This is the fastest and most direct way to check for cordoned worker nodes, as the output immediately shows which nodes have scheduling disabled. No additional flags or subcommands are needed.

Answer

oc get machineconfigpool --cordoned

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oc describe clusteroperator scheduling

Answer

oc adm show-cordoned

Question 10

An administrator has modified a KubeletConfig resource to adjust the pod eviction thresholds on worker nodes. After applying the change, the administrator observes that some worker nodes are updating while others belonging to a custom worker pool are not. What is the most likely reason?

Accepted Answer

The KubeletConfig's machineConfigPoolSelector does not match the labels on the custom MachineConfigPool.. The KubeletConfig resource uses a machineConfigPoolSelector to target specific MachineConfigPools (MCPs). If the selector does not match the labels on the custom worker pool's MCP, the KubeletConfig will not be applied to nodes in that pool. This is the most likely reason why some nodes update while others do not.

Answer

KubeletConfig objects are only supported on control plane nodes in OpenShift 4.14.

Answer

The cluster storage size is insufficient to hold the new kubelet configuration.

Answer

The kubelet service must be manually restarted on every node using SSH.

Question 11

An administrator has successfully installed an Operator via OperatorHub, but the Operator's CSV (ClusterServiceVersion) status is stuck at 'Pending'. Upon investigating, the administrator discovers that the required CustomResourceDefinitions (CRDs) have conflicting versions with a previously deleted Operator. How can the administrator forcefully clean up orphaned CRDs if OLM fails to remove them?

Accepted Answer

Edit the CRD definition and remove any lingering finalizers in 'metadata.finalizers' to allow deletion.. When OLM fails to remove a CRD because it is stuck in Terminating, the usual cause is a lingering finalizer in metadata.finalizers. Editing the CRD to remove the finalizer allows the Kubernetes API server to complete deletion, clearing the orphaned CRD so the new Operator's CSV can proceed past Pending.

Answer

Run 'oc adm prune crds --force' to automatically purge all stuck custom resources.

Answer

Restart the kube-apiserver pods to bypass CRD validation checks.

Answer

Delete the openshift-operator-lifecycle-manager namespace to reset all CRDs.

Question 12

Which custom resource defines a group of nodes (such as all worker nodes or a custom compute pool) that share a common MachineConfig in OpenShift 4.14?

Accepted Answer

MachineConfigPool. A MachineConfigPool (MCP) groups nodes that share the same MachineConfig, such as all worker nodes (the 'worker' pool) or a custom pool like 'infra'. The Machine Config Operator (MCO) applies MachineConfigs to nodes based on their pool membership, and each pool has its own rendered MachineConfig. This is the resource that defines a set of nodes with a common configuration.

Answer

NodeGroup

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MachineSet

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ConfigMap

Question 13

An administrator needs to inspect the current update channel and version of an OpenShift 4.14 cluster. Which command provides this status directly?

Accepted Answer

oc get clusterversion. The `oc get clusterversion` command retrieves the ClusterVersion custom resource, which contains the cluster's current version and update channel. This resource is the authoritative source for OpenShift update status, including available updates and the desired channel. It directly answers the administrator's need to inspect both the update channel and version.

Answer

oc version --cluster

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oc get nodes --version

Answer

oc describe operator cluster

Question 14

What is the purpose of the 'oc adm drain' command during cluster maintenance?

Accepted Answer

To mark a node unschedulable and gracefully evict workloads running on it.. The 'oc adm drain' command is used to safely evict all pods from a node before maintenance, such as rebooting or upgrading. It marks the node as unschedulable (cordon) and then evicts pods, respecting PodDisruptionBudgets. This ensures workloads are gracefully moved to other nodes, minimizing downtime.

Answer

To restart the kubelet service and flush local DNS caches.

Answer

To permanently delete the node and its virtual machine instance from the cloud provider.

Answer

To clear container logs and free up disk space on the node filesystem.

Question 15

An administrator installed an Operator via OperatorHub and selected a specific update channel. Later, the administrator wants to switch the Subscription to a different update channel. How should this be performed?

Accepted Answer

Edit the Subscription custom resource and modify the 'spec.channel' field to the new channel.. To switch an Operator's update channel, you edit the Subscription custom resource and change the spec.channel field to the desired channel name. The Operator Lifecycle Manager (OLM) then reconciles the Subscription and upgrades/downgrades the Operator to the latest version available in that channel. This is the supported and non-disruptive method.

Answer

Delete the Operator's CSV and reinstall the Operator from scratch via the CLI.

Answer

Modify the OperatorGroup target namespace to force a channel renegotiation.

Answer

Patch the ClusterServiceVersion directly with the new channel identifier.