KCNA Exam Dumps - Linux Foundation Kubernetes and Cloud Native Questions and Answers

Kubernetes groups and organizes objects primarily usinglabels, soBis correct. Labels are key-value pairs attached to objects (Pods, Deployments, Services, Nodes, etc.) and are intended to be used for identifying, selecting, and grouping resources in a flexible, user-defined way.

Labels enable many core Kubernetes behaviors. For example, aServiceselects the Pods that should receive traffic by matching alabel selectoragainst Pod labels. A Deployment’s ReplicaSet similarly uses label selectors to determine which Pods belong to the replica set. Operators and platform tooling also rely on labels to group resources by application, environment, team, or cost center. This is why labeling is considered foundational Kubernetes hygiene: consistent labels make automation, troubleshooting, and governance easier.

A “label selector” (option C) is how you query/group objects based on labels, but the underlying primary mechanism is still thelabelsthemselves. Without labels applied to objects, selectors have nothing to match. Custom Resources (option A) extend the API with new kinds, but they are not the primary grouping mechanism across the cluster. “Pod” (option D) is a workload unit, not a grouping mechanism.

Practically, Kubernetes recommends common label keys like app.kubernetes.io/name, app.kubernetes.io/instance, and app.kubernetes.io/part-of to standardize grouping. Those conventions improve interoperability with dashboards, GitOps tooling, and policy engines.

So, when the question asks for the primary mechanism used to identify grouped objects in Kubernetes, the most accurate answer isLabels (B)—they are the universal metadata primitive used to group and select resources.

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To scale on custom, application-generated metrics, the Horizontal Pod Autoscaler (HPA) needs those metrics exposed through the Kubernetescustom metrics(or external metrics) API. A common and Kubernetes-documented approach isPrometheus + prometheus-adapter, makingAcorrect. Prometheus scrapes application metrics (for example, request rate, queue depth, in-flight requests) from /metrics endpoints. Theprometheus-adapterthen translates selected Prometheus time series into the Kubernetes Custom Metrics API so the HPA controller can fetch them and make scaling decisions.

Why not the other options:Grafanais a visualization tool; it does not provide the metrics API translation layer required by HPA, so “Grafana and Prometheus” is incomplete. Graylog is primarily a log management system; it’s not the standard solution for feeding custom metrics into HPA via the Kubernetes metrics APIs. The “kubernetes-adapter” term in option C is not the standard named adapter used in the common Kubernetes ecosystem for Prometheus-backed custom metrics (the recognized component is prometheus-adapter).

This matters operationally because HPA is not limited to CPU/memory. CPU and memory use resource metrics (often from metrics-server), but modern autoscaling often needs application signals: message queue length, requests per second, latency, or business metrics. With Prometheus and prometheus-adapter, you can define HPA rules such as “scale to maintain queue depth under X” or “scale based on requests per second per pod.” This can produce better scaling behavior than CPU-based scaling alone, especially for I/O-bound services or workloads with uneven CPU profiles.

So the correct tooling combination in the provided choices isPrometheus and the prometheus-adapter, optionA.

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Any Kubernetes object manifest must includeapiVersion,kind, andmetadata, which makesAcorrect. This comes directly from how Kubernetes resources are represented and processed by the API server.

apiVersiontells Kubernetes which API group and version should be used to interpret the object (for example v1, apps/v1, batch/v1). This matters because schemas and available fields can change between versions.

kindspecifies the type of object you are creating (for example Pod, Service, Deployment, ConfigMap). Kubernetes uses this to route the request to the correct API endpoint and schema.

metadatacontains identifying and organizational information such as name, namespace (when namespaced), labels, and annotations. At minimum, most objects require a name; labels and annotations are optional but extremely common for selection and tooling.

A common point of confusion isspec. Many Kubernetes objects include spec because they define desired state (like a Deployment’s replica count, Pod template, update strategy). However, the question asks what fields must exist inanyKubernetes object file. Not all objects require a spec in the same way (and some objects include other top-level sections like data for ConfigMaps/Secrets or rules for RBAC objects). The truly universal top-level requirements are the trio in option A.

Options B, C, and D include fields that are not universally required (namespace is not required for cluster-scoped objects, and data only applies to certain kinds like ConfigMaps/Secrets). Therefore,apiVersion + kind + metadatais the correct, general rule and matches Kubernetes object structure.

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The correct answer isD: CronJob. A Kubernetes CronJob is specifically designed for creating Jobs on a schedule—either at specified times/dates (expressed via cron syntax) or on a repeating interval (hourly, daily, weekly). When the schedule triggers, the CronJob controller creates aJob, and the Job controller creates the Pods that execute the workload to completion.

Option A (Job) is not inherently scheduled. A Job runs when you create it, and it continues until it completes successfully or fails according to its retry/backoff behavior. If you want it to run periodically, you need something else to create the Job each time. CronJob is the built-in mechanism for that scheduling.

Options B and C are not standard Kubernetes workload objects. Kubernetes does not include “CalendarJob” or “BatchJob” as official API kinds. The scheduling primitive is CronJob.

CronJobs also include important operational controls: concurrency policies prevent overlapping runs, deadlines control missed schedules, and history limits manage old Job retention. This makes CronJobs more robust than ad-hoc scheduling approaches and keeps the workload lifecycle visible in the Kubernetes API (status/events/logs). It also means you can apply standard Kubernetes patterns: use a service account with least privilege, mount Secrets/ConfigMaps, run in specific namespaces, and manage resource requests/limits so that scheduled workloads don’t destabilize the cluster.

So the correct Kubernetes resource for scheduled and repeating job execution isCronJob (D).

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The correct answer isA: Metrics, Logs, and Traces. These are widely recognized as the “three pillars” because together they provide complementary views into system behavior:

Metricsare numeric time series collected over time (CPU usage, request rate, error rate, latency percentiles). They are best for dashboards, alerting, and capacity planning because they are structured and aggregatable. In Kubernetes, metrics underpin autoscaling and operational visibility (node/pod resource usage, cluster health signals).

Logsare discrete event records (often text) emitted by applications and infrastructure components. Logs provide detailed context for debugging: error messages, stack traces, warnings, and business events. In Kubernetes, logs are commonly collected from container stdout/stderr and aggregated centrally for search and correlation.

Tracescapture the end-to-end journey of a request through a distributed system, breaking it into spans. Tracing is crucial in microservices because a single user request may cross many services; traces show where latency accumulates and which dependency fails. Tracing also enables root cause analysis when metrics indicate degradation but don’t pinpoint the culprit.

Why the other options are wrong: aspanis a componentwithintracing, not a top-level pillar; “data” is too generic; and “resources” are not an observability signal category. The pillars are defined by signal type and how they’re used operationally.

In cloud-native practice, these pillars are often unified via correlation IDs and shared context: metrics alerts link to logs and traces for the same timeframe/request. Tooling like Prometheus (metrics), log aggregators (e.g., Loki/Elastic), and tracing systems (Jaeger/Tempo/OpenTelemetry) work together to provide a complete observability story.

Therefore, the verified correct answer isA.

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kubectl explain is the command that showsdocumentation and field definitionsfor Kubernetes resource schemas, soAis correct. Kubernetes resources have a structured schema: top-level fields like apiVersion, kind, and metadata, and resource-specific structures like spec and status. kubectl explain lets you explore these structures directly from your cluster’s API discovery information, including field types, descriptions, and nested fields.

For example, kubectl explain deployment describes the Deployment resource, and kubectl explain deployment.spec dives into the spec structure. You can continue deeper, such as kubectl explain deployment.spec.template.spec.containers to discover container fields. This is especially useful when writing or troubleshooting manifests, because it reduces guesswork and prevents invalid YAML fields that would be rejected by the API server. It also helps when APIs evolve: you can confirm which fields exist in your cluster’s current version and what they mean.

The other commands do different things. kubectl api-resources lists resourcetypesand their shortnames, whether they are namespaced, and supported verbs—useful discovery, but not detailed field definitions. kubectl get --help shows CLI usage help for kubectl get, not the Kubernetes object schema. kubectl show is not a standard kubectl subcommand.

From a Kubernetes “declarative configuration” perspective, correct manifests are critical: controllers reconcile desired state from spec, and subtle field mistakes can change runtime behavior. kubectl explain is a built-in way to learn the schema and write manifests that align with the Kubernetes API’s expectations. That’s why it’s commonly recommended in Kubernetes documentation and troubleshooting workflows.

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The true statement isC: the default namespace exists when a new cluster is created. Namespaces are a Kubernetes mechanism for partitioning cluster resources into logical groups. When you set up a cluster, Kubernetes creates some initial namespaces (including default, and commonly kube-system, kube-public, and kube-node-lease). The default namespace is where resources go if you don’t specify a namespace explicitly.

Option A is false because namespaces are not hierarchical; Kubernetes does not support “namespaces inside namespaces.” Option B is false because within a given namespace, resource names must be unique per resource kind. You can’t have two Deployments with the same name in the same namespace. Youcanhave a Deployment named web in one namespace and another Deployment named web in a different namespace—namespaces provide that scope boundary. Option D is false because not all objects are namespaced. Many resources arecluster-scoped(for example, Nodes, PersistentVolumes, ClusterRoles, ClusterRoleBindings, and StorageClasses). Namespaces apply only to namespaced resources.

Operationally, namespaces support multi-tenancy and environment separation (dev/test/prod), RBAC scoping, resource quotas, and policy boundaries. For example, you can grant a team access only to their namespace and enforce quotas that prevent them from consuming excessive CPU/memory. Namespaces also make organization and cleanup easier: deleting a namespace removes most namespaced resources inside it (subject to finalizers).

So, the verified correct statement isC: the default namespace exists upon cluster creation.

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The correct answer isB: GitOps helps reduce failed deployments, reduce configuration drift, and reduce fragile release processes. GitOps is an operating model whereGit is the source of truthfor declarative configuration (Kubernetes manifests, Helm releases, Kustomize overlays). A GitOps controller (like Flux or Argo CD) continuously reconciles the cluster’s actual state to match what’s declared in Git. This creates a stable, repeatable deployment pipeline and minimizes “snowflake” environments.

Reducing failed deployments: changes go through pull requests, code review, automated checks, and controlled merges. Deployments become predictable because the controller applies known-good, versioned configuration rather than ad-hoc manual commands. Rollbacks are also simpler—reverting a Git commit returns the cluster to the prior desired state.

Reducing configuration drift: without GitOps, clusters often drift because humans apply hotfixes directly in production or because different environments diverge over time. With GitOps, the controller detects drift and either alerts or automatically corrects it, restoring alignment with Git.

Reducing fragile release processes: releases become standardized and auditable. Git history provides an immutable record of who changed what and when. Promotion between environments becomes systematic (merge/branch/tag), and the same declarative artifacts are used consistently.

The other options include items that are either not the primary GitOps promise (like “learn git”) or subjective (“improve your reputation”). Operational cost reduction can happen indirectly through fewer incidents and more automation, but the most canonical and direct GitOps advantages in Kubernetes delivery are reliability and drift control—captured precisely inB.

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If a Pod is waiting for its container images to be pulled to the node, it remains in thePendingphase, soDis correct. Kubernetes Pod “phase” is a high-level summary of where the Pod is in its lifecycle.Pendingmeans the Pod has been accepted by the cluster but one or more of its containers has not started yet. That can occur because the Pod is waiting to be scheduled, waiting on volume attachment/mount, or—very commonly—waiting for the container runtime to pull the image.

When image pulling is the blocker, kubectl describe pod usually shows events like “Pulling image …” and “Successfully pulled image …” or failures like ImagePullBackOff/ErrImagePull. Even if the node has been assigned (scheduler has set spec.nodeName), the Pod can still be Pending while kubelet and the runtime perform preparation steps.

Why the other phases don’t apply:

Succeededis for run-to-completion Pods that have finished successfully (typical for Jobs).

Failedmeans the Pod terminated and at least one container terminated in failure (and won’t be restarted, depending on restartPolicy).

Unknownis used when the node can’t be contacted and the Pod’s state can’t be reliably determined (rare in healthy clusters).

A subtle but important Kubernetes detail: status “Waiting” reasons like ImagePullBackOff are container states inside .status.containerStatuses, while the Pod phase can still be Pending. So, “waiting for images to download” maps to Pod Pending, with container waiting reasons providing the deeper diagnosis.

Therefore, the verified correct answer isD: Pending.

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Argo Workflows (D)is the correct answer because it is a Kubernetes-native workflow engine designed to define and run multi-step workflows—often withparallelization—directly on Kubernetes. Argo Workflows models workflows as DAGs (directed acyclic graphs) or step-based sequences, where each step is typically a Pod. Because each step is expressed as Kubernetes resources (custom resources), Argo can schedule many tasks concurrently, control fan-out/fan-in patterns, and manage dependencies between steps (e.g., “run these 10 jobs in parallel, then aggregate results”).

The question calls it a “GitOps engine,” but the capability being tested is “orchestrate parallel jobs.” Argo Workflows fits because it is purpose-built for running complex job orchestration, including parallel tasks, retries, timeouts, artifacts passing, and conditional execution. In practice, many teams store workflow manifests in Git and apply GitOps practices around them, but the distinguishing feature here is the workflow orchestration engine itself.

Why the other options are not best:

Flux (C)is a GitOps controller that reconciles cluster state from Git; it doesn’t orchestrate parallel job graphs as its core function.

Flagger (B)is a progressive delivery operator (canary/blue-green) often paired with GitOps and service meshes/Ingress; it’s not a general workflow orchestrator for parallel batch jobs.

Jenkins X (A)is CI/CD-focused (pipelines), not primarily a Kubernetes-native workflow engine for parallel job DAGs in the way Argo Workflows is.

So, the Kubernetes-native tool specifically used to orchestrate parallel jobs and workflows isArgo Workflows (D).

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