Cloud & DevOps interview questions
95 Cloud & DevOps interview questions with answers, from junior to mid level.
Foundations
- What does 'deploy' mean in software?
- What is a terminal (command line) and what is a shell?
- What is Linux, and why does it matter for backend and cloud work?
- What is DevOps?
- What problem does Docker solve?
- What is the difference between a Docker image and a container?
- What is Kubernetes (also written K8s)?
- In Kubernetes, what are a cluster, a node and a Pod?
- What is a cloud provider, and which are the three largest?
- What are the five essential characteristics of cloud computing according to NIST?
- What are IaaS, PaaS and SaaS?
- What is a virtual machine (VM)?
- In AWS, what are a Region and an Availability Zone (AZ)?
- What is Amazon EC2?
- What are Amazon S3 and Azure Blob Storage?
- What is Microsoft Entra ID?
- What is Infrastructure as Code (IaC)?
- What are logs and monitoring?
- What do CI and CD stand for?
- Explain Docker, Kubernetes and the cloud to a friend with no technical background.
- What is the difference between a virtual machine and a container?
Core
- What is the key difference between a container and a virtual machine?
- Why mount a volume for a PostgreSQL container?
- What is Docker Compose mainly used for?
- What is Amazon S3?
- Docker image vs container?
- What is a Dockerfile?
- What does
-p 8080:8000mean indocker run -p 8080:8000 myapp? - What is Continuous Integration (CI)?
- What does 'running in the cloud' basically mean?
- Why read
DATABASE_URLfrom an environment variable instead of writing it in the code? - What is Kubernetes mainly used for?
- What is a staging environment?
- In a containerized app, where should application logs go?
- What is SSH used for?
- Which Docker commands list running containers and show a container's logs?
- What are Kubernetes namespaces for?
- Which
kubectlcommands apply a manifest, list Pods and read a Pod's logs? - What is a container registry, and what are examples?
- Which AWS service is closest to a rented virtual server, and which runs code without managing servers?
- Which pairs of AWS and Azure services are equivalent?
- What does the CIDR notation
10.0.1.0/24mean? - What is the difference between a public IP, a private IP and NAT?
- What is the shared responsibility model in the cloud?
- IaaS, PaaS and SaaS: which examples match?
- Explain the main building blocks of cloud networking.
Intermediate
- Which Dockerfile ordering makes rebuilds fastest when only your source code changes?
- Why use a multi-stage Docker build?
CMDvsENTRYPOINTin a Dockerfile?- A container starts and exits immediately with code 0. Most likely cause?
- In Kubernetes, what is a Pod?
- Which Kubernetes object manages rolling updates and keeps N replicas running?
- What does a Kubernetes Service provide?
- Where should a database password go in Kubernetes?
- Continuous Delivery vs Continuous Deployment?
- Which order makes the most sense for a CI/CD pipeline?
- What does
terraform plando? - According to the Twelve-Factor App, where should configuration that varies between environments live?
- Which is a known limitation of AWS Lambda?
- How should an app running on EC2 or ECS access S3?
- How do you make a service resilient to a single data center failure on AWS?
- What do feature flags let you do?
- On a Linux server, which command shows which process is listening on port 8000?
- In a blameless postmortem, the focus is on…
- Describe a CI/CD pipeline you would set up for a Python web service.
- Production breaks right after a deploy. What do you do?
- What does this Dockerfile for a Spring Boot app do?
- In Kubernetes, what is the difference between a ConfigMap and a Secret?
- What are the Kubernetes Service types ClusterIP, NodePort and LoadBalancer, and what is an Ingress?
- What does this manifest declare?
- When would you use a StatefulSet, a DaemonSet, a Job or a CronJob instead of a Deployment?
- A Pod shows
CrashLoopBackOff. What does it mean and how do you start debugging? - What is the difference between Kubernetes resource
requestsandlimits? - What is Helm?
- What are PersistentVolumes (PV) and PersistentVolumeClaims (PVC)?
- ECS vs EKS vs Fargate: what do they mean?
- RDS vs DynamoDB: when do you choose each?
- In AWS networking, what is a VPC and the difference between a public and a private subnet?
- Security Group vs Network ACL (AWS): which statement is correct?
- What is the difference between an Application Load Balancer (ALB) and a Network Load Balancer (NLB)?
- How is Azure organized: subscription, resource group and resource?
- What is the difference between DNS record types A, CNAME and MX?
- Which native Infrastructure-as-Code tools exist for each cloud?
- Which CI/CD tools are commonly used with Java projects?
- You have a Spring Boot service. Describe how you would containerize it and run it on Kubernetes in AWS or Azure.
- How do you choose between VMs, containers (Kubernetes) and serverless?
Advanced
- A container is killed with exit code 137. What usually happened?
- Readiness probe vs liveness probe?
- SQS vs SNS?
- What is immutable infrastructure?
- What does Kubernetes' Horizontal Pod Autoscaler do?
- What is an Azure Managed Identity (and the AWS equivalent for workloads)?
- How can a private app in your VPC/VNet reach a cloud service (e.g. S3 or Azure Storage) without going over the public internet?
- How do you connect an on-premises network (a company office or data center) to your cloud network?
- How do you make a web service highly available across failures in AWS or Azure?