Easy interview questions in Docker & Kubernetes, page 2
What are PersistentVolumes and PersistentVolumeClaims for?
A PV is a cluster storage resource the admin provisions; a PVC is a user's request for size and access mode; Kubernetes binds them, decoupling Pods from storage details.
What happens to volume data when a Pod is deleted?
EmptyDir is tied to the Pod and erased when the Pod is deleted; a PVC-backed PV with Retain keeps the data after the PVC is released for manual recovery.
Bind mounts vs named volumes for persisting Docker data?
Persist data outside the writable container layer via a bind mount (a host path you control) or a named volume (Docker-managed under its data dir, portable and the recommended default).
Requests vs limits for CPU and memory?
Requests guide scheduling and reservation, limits cap usage; exceeding a CPU limit throttles the container, while exceeding a memory limit triggers an OOMKill since memory is incompressible.
How do you pin a Pod to nodes with a given label?
The simplest tool is nodeSelector, a key-value map in the Pod spec requiring matching node labels; node affinity is the richer alternative for complex rules.
How do you stop new Pods scheduling on a node?
Kubectl cordon marks the node unschedulable so no new Pods land, while existing Pods keep running; drain is the follow-up that also evicts them.
Role versus ClusterRole in RBAC
Role is namespaced, ClusterRole is cluster-wide and covers cluster-scoped resources, and you grant either via a RoleBinding (namespaced) or ClusterRoleBinding (cluster-wide) to a subject.
First NetworkPolicy flips a pod to default-deny
Once any policy selects a pod for a direction, that direction becomes default-deny and only explicitly allowed traffic passes; unselected pods stay open.
Viewing pod logs and durable log collection
Kubectl logs (with -c, --previous, -f) reads container stdout/stderr; because that storage is ephemeral, run a node-level logging agent as a DaemonSet shipping logs to a central store.
kube-state-metrics versus node-exporter
Kube-state-metrics exposes API object state (deployment replicas, pod phase, restarts) from the control plane, while node-exporter exposes OS-level hardware metrics (CPU, memory, disk) per…
What is a Helm chart?
A chart is a templated, versioned bundle of manifests with a values file; it solves config duplication and reuse across environments.
What is the basic principle of GitOps?
Git holds desired state; a controller continuously reconciles the cluster to match it; benefits are auditability, rollback, and drift correction.
Override Helm values at install time
Pass custom files with -f or --values, single keys with --set, and know precedence: defaults, then files, then --set.
What is a Custom Resource Definition?
A CRD registers a new resource kind so the API server stores and serves it like built-ins; it lets you model domain concepts declaratively.
Core components of a Kubernetes Operator
A CRD defines the type, a controller watches instances via the API server and runs a reconcile loop, encoding operational knowledge to drive real state.
Creating an instance of a custom resource
Write a manifest with apiVersion (group/version), kind, metadata.name, and a spec matching the CRD schema, then kubectl apply -f it.
What a service mesh solves
It adds traffic management, security via mTLS, and observability at the network layer through sidecars, beyond what plain Kubernetes offers.
The sidecar proxy pattern in a mesh
A proxy container shares the pod, all in/out traffic is redirected through it, so policy and telemetry apply without code changes.
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