Kubernetes Interview Questions and Answers

Answer: Role-Based Access Control for authorization

RBAC is a method for regulating access to resources. Uses Roles/ClusterRoles to define permissions and Bindings to assign them.

Answer: An open-source container orchestration platform

Kubernetes (K8s) is an open-source container orchestration platform that automates deployment, scaling, and management of containerized applications.

Answer: Role is namespaced, ClusterRole is cluster-wide

Role grants permissions within a namespace. ClusterRole grants cluster-wide permissions or access to cluster-scoped resources.

Answer: The smallest deployable unit containing one or more containers

A Pod is the smallest deployable unit in Kubernetes. It represents one or more containers that share network and storage resources.

Answer: Command-line tool for interacting with Kubernetes

kubectl is the command-line tool for communicating with a Kubernetes cluster. It allows you to run commands against clusters.

Answer: Both a and b

Use envFrom with configMapRef in Pod spec to mount ConfigMap as environment variables. All keys become environment variables.

Answer: Extends Kubernetes API with custom resource types

CRD extends the Kubernetes API by defining custom resource types. Enables operators and custom controllers for domain-specific resources.

Answer: kubectl get pods

`kubectl get pods` lists all Pods in the current namespace. Add `-A` or `--all-namespaces` to see Pods across all namespaces.

Answer: Application-specific controller using CRDs

Operator is application-specific controller that uses CRDs. Automates operational tasks like deployment, scaling, backup, recovery.

Answer: Codifies operational knowledge into software

Operator pattern codifies operational knowledge into software. Custom controller watches custom resources and takes action to maintain desired state.

Answer: Virtual cluster for logical isolation

Namespaces provide logical isolation for resources within a cluster. They enable multi-tenancy and resource organization.

Answer: Stable network endpoint that abstracts access to Pods

A Service is an abstraction that defines a logical set of Pods and a policy to access them. It provides stable networking and load balancing.

Answer: Package manager for Kubernetes using charts

Helm is a package manager for Kubernetes. Uses charts (packages) with templates to simplify application deployment and management.

Answer: Manages ReplicaSets and provides declarative updates for Pods

A Deployment manages ReplicaSets and provides declarative updates for Pods. It handles rolling updates, rollbacks, and scaling.

Answer: Package of Kubernetes resources with templates

Helm Chart is a package containing Kubernetes resource templates and default values. Charts are reusable and can be shared via repositories.

Answer: Template-free customization with overlays

Kustomize provides template-free customization of Kubernetes configs. Uses overlays and patches. Integrated into kubectl with -k flag.

Answer: Manages external HTTP/HTTPS access to Services

Ingress manages external access to Services, typically HTTP/HTTPS. Provides load balancing, SSL termination, and name-based virtual hosting.

Answer: Set of components that manage the cluster

The control plane manages the Kubernetes cluster. Components include API server, scheduler, controller manager, and etcd.

Answer: Implements Ingress rules as Pods

Ingress Controller implements Ingress rules. It must be installed separately (nginx-ingress, traefik, etc.) and runs as Pods.

Answer: Intercepts API requests before persisting to etcd

Admission Controllers intercept API requests before persisting to etcd. Can validate or mutate requests. Examples: PodSecurityPolicy, ResourceQuota.

Answer: Ensures Pod runs on all Nodes

DaemonSet ensures a copy of a Pod runs on all (or some) Nodes. Used for node-level services like log collection and monitoring.

Answer: Manages stateful applications with stable identities

StatefulSet manages stateful applications. Provides stable network identities, persistent storage, and ordered deployment/scaling.

Answer: Custom admission controller that validates and can reject requests

ValidatingAdmissionWebhook validates objects and can reject requests. Runs after mutating webhooks. Used for custom validation logic.

Answer: kubectl apply -f file.yaml

`kubectl apply -f file.yaml` creates or updates resources declaratively. `kubectl create -f` also works but apply is preferred for updates.