DevOps Engineer interview questions and answers.

Questions

Technical questions to practise out loud

1. 01

   What is the difference between containers and virtual machines?

   Virtual machines emulate hardware and run separate kernels, giving stronger isolation at higher overhead; containers share the host kernel and package processes, starting faster and denser but with a shared security boundary.

   Read the full breakdown
2. 02

   What is the difference between readiness and liveness probes?

   Readiness decides whether a pod receives traffic; liveness decides whether Kubernetes restarts it. A dependency outage should usually fail readiness, not liveness, or restarts can amplify the incident.

   Read the full breakdown
3. 03

   How do you triage a service incident?

   Establish impact and severity, assign command and communications, check recent changes and core service signals, mitigate the largest user harm first, preserve evidence, and record a timeline before deep root-cause work.

   Read the full breakdown
4. 04

   How do you reduce a Docker image size?

   Use a minimal trusted base, multi-stage builds, a strict .dockerignore, deterministic dependency layers, production-only packages, and no package caches or build tools in the final stage; inspect layers and scan the result.

   Read the full breakdown
5. 05

   How do you debug a Kubernetes OOMKilled pod?

   Confirm the container termination reason and memory limit, correlate usage and restarts, inspect heap, allocations and workload, distinguish a leak from an undersized limit, then fix memory behavior or set measured requests and limits.

   Read the full breakdown
6. 06

   How do you manage Terraform state safely?

   Store Terraform state in an encrypted remote backend with locking, versioning, restricted identities and backups; separate environments, never edit state casually, review plans, and use import or state commands under controlled change.

   Read the full breakdown
7. 07

   How do you design CI/CD for a web service?

   CI builds one immutable artifact and runs lint, tests, security and migration checks; CD promotes that same artifact through environments with approvals where needed, progressive rollout, health gates, observability and rollback.

   Read the full breakdown
8. 08

   What makes infrastructure as code maintainable?

   Maintainable IaC uses small owned modules, explicit inputs and outputs, pinned providers, remote state, automated formatting and validation, reviewed plans, policy checks, drift detection, and documentation of lifecycle and migration.

   Read the full breakdown
9. 09

   How do you roll out a Kubernetes deployment safely?

   Roll out with immutable images, realistic readiness and startup probes, resource requests, a rolling or canary strategy, disruption limits, monitored error and latency gates, automatic pause, and a tested rollback path.

   Read the full breakdown
10. 10

    How do you manage infrastructure secrets?

    Keep secrets in a dedicated encrypted manager, issue identities instead of static keys where possible, grant least privilege, inject at runtime, avoid logs and images, rotate automatically, audit access, and test revocation.

    Read the full breakdown