DevOps & Cloud · 2026 Edition

Top 50 DevOps & Kubernetes Interview Questions & Answers for 2026

·20 min read·Intervio DevOps Experts

Key Takeaways — DevOps & SRE Interviews 2026

  • •Kubernetes Architecture Mastery: Deep knowledge of kube-apiserver, etcd Raft consensus, kube-scheduler filters, kube-controller-manager loops, and CNI plugins (Calico/Cilium) is tested in 90% of DevOps interviews.
  • •IaC & Terraform State: Terraform remote backend state locking with DynamoDB and S3, module versioning, drift detection, and lifecycle { prevent_destroy = true } rules.
  • •Zero-Downtime Deployment Patterns: Clear distinction between Rolling Updates, Blue-Green, Canary deployments with Flagger/Istio, and GitOps synchronization via ArgoCD.
  • •Linux & Production Troubleshooting: Systematic incident debugging using strace, lsof, ss/netstat, tcpdump, journalctl, and resolving CrashLoopBackOff and OOMKilled statuses.

1. Kubernetes Cluster Architecture & Control Plane Internals

Kubernetes coordinates declarative state through a distributed control plane. Interviewers expect candidates to describe how an API request moves through each component.

1. kube-apiserver

The only component that communicates with etcd. Validates, authenticates, and configures data for pod, service, replication controller objects.

2. etcd

Consistent, highly-available key-value store using Raft consensus to persist cluster state. Requires an odd number of nodes (3 or 5) for quorum (N/2 + 1).

3. kube-scheduler

Assigns unscheduled pods to worker nodes via two phases: Filtering (Predicates) to find eligible nodes, and Scoring (Priorities) to choose the best node.

4. kubelet

Node agent ensuring containers described in PodSpecs are running and healthy via the Container Runtime Interface (CRI).

2. Troubleshooting Pods: CrashLoopBackOff, OOMKilled & Pending

CrashLoopBackOff: Root Causes & Fixes

Indicates a pod starts, fails, restarts, and crashes repeatedly with exponential backoff delay.

# Debugging step-by-step:
kubectl describe pod <pod-name> -n <namespace>
kubectl logs <pod-name> --previous
# Common causes: Application fatal exception, missing environment variable/ConfigMap, permission error.

OOMKilled (Exit Code 137)

The container exceeded its configured memory limit and was terminated by the Linux kernel Out-Of-Memory killer. Fix: Increase resources.limits.memory or diagnose memory leaks in the app runtime.

3. Docker Multi-Stage Builds & Security Hardening

Writing production-grade Dockerfiles requires minimizing image size and eliminating root privileges. 

# Stage 1: Build stage with compiler tools
FROM golang:1.24-alpine AS builder
WORKDIR /app
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN CGO_ENABLED=0 GOOS=linux go build -o server . # Stage 2: Minimal runtime image without build bloat
FROM alpine:3.20
RUN adduser -D -u 10001 appuser
USER appuser
COPY --from=builder /app/server /usr/local/bin/server
EXPOSE 8080
ENTRYPOINT ["/usr/local/bin/server"]

4. Terraform & Infrastructure as Code Best Practices

Key questions asked about Terraform state management and security:

  • Remote Backend & Locking: Storing state in AWS S3 with encryption and using DynamoDB for state locking prevents concurrent executions from corrupting infrastructure state.
  • Terraform Drift: When physical cloud resources change outside Terraform. Detected with terraform plan -refresh-only and aligned with terraform apply -refresh-only.
  • Terraform Modules: Promote DRY (Don't Repeat Yourself) infrastructure patterns, enabling environment parity between Dev, Staging, and Production.

5. CI/CD, GitOps (ArgoCD) & Progressive Delivery

Modern deployment pipelines rely on declarative Git repositories as the single source of truth:

GitOps with ArgoCD & Flux

ArgoCD runs inside the Kubernetes cluster and continuously monitors Git repos. If cluster state drifts from the committed manifests, it automatically reconciles or alerts engineers.

Progressive Delivery & Automated Rollbacks

Using Argo Rollouts or Flagger to automate Canary releases with Prometheus metrics analysis (HTTP error rates, p99 latency) triggers immediate automated rollbacks if thresholds are breached.

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6. Frequently Asked DevOps Interview Questions

What is the difference between a Deployment and a StatefulSet in Kubernetes?

A Deployment manages stateless application replicas with random pod names and shared storage, suitable for web servers. A StatefulSet provides unique, persistent ordinal pod identities (e.g., kafka-0, kafka-1), dedicated persistent volume claims per pod, and ordered startup/shutdown guarantees, essential for databases and distributed consensus nodes.

What is the difference between Blue-Green and Canary deployments?

In Blue-Green deployment, two identical production environments exist; 100% of live traffic flips instantaneously from Blue (old) to Green (new). In Canary deployment, new software is deployed alongside existing versions and receives a small percentage of user traffic (e.g., 5%) while metrics are analyzed before gradually scaling to 100%.