76 DevOps & Cloud Essentials interview questions with answers (2026)

All DevOps & Cloud Essentials interview questions

Blue-green vs canary deployment — what is the difference?

What is the difference between a Docker image and a container?

What is a Dockerfile and what are the common instructions?

How do Docker layers and the build cache work?

What is a multi-stage build and what problem does it solve?

How do volumes and bind mounts differ, and why are they needed?

What are the Docker network drivers?

What is Docker Compose used for?

How do you reduce Docker image size?

What is a Pod in Kubernetes?

What is the difference between a Deployment and a ReplicaSet?

What is a Kubernetes Service and what types exist?

How does Ingress differ from a LoadBalancer Service?

What is the difference between a ConfigMap and a Secret?

What are Kubernetes namespaces used for?

How does the Horizontal Pod Autoscaler (HPA) work?

What is the difference between liveness and readiness probes?

How do rolling updates and rollbacks work in a Deployment?

How does a StatefulSet differ from a Deployment, and when do you use it?

What is a CI/CD pipeline and what stages does it have?

Distinguish Continuous Integration, Delivery and Deployment.

What is an artifact in CI/CD?

What is Amazon EC2?

What is Amazon S3 and its key characteristics?

What is the difference between an IAM role and an IAM policy?

What is a VPC and what are its components?

How do ALB and NLB differ, and when do you use each?

How does AWS Auto Scaling work?

What is Amazon RDS and its benefit over self-managing a DB on EC2?

What are AWS Lambda and serverless?

What is CloudFront (a CDN) and what problem does it solve?

What is the difference between a Region and an Availability Zone (AZ)?

What is the difference between high availability and fault tolerance?

What is a process in Linux, and how do you inspect/manage it?

What are Linux signals, and how do SIGTERM and SIGKILL differ?

How do you read Linux file permissions, and what does `chmod 755` mean?

What is systemd and what is it used for?

What is cron used for and how do you read a cron schedule?

How do TCP and UDP differ, and when do you use each?

What is the difference between HTTP and HTTPS?

What is DNS and how does name resolution work?

What is load balancing, and how do L4 and L7 differ?

What is the difference between a reverse proxy and a forward proxy?

What is a firewall, and how do security groups differ from Network ACLs?

What is the 12-factor app and some of its key principles?

What is Infrastructure as Code (IaC), and what does Terraform solve?

How do monitoring, logging and observability differ?

What is secrets management, and why not hardcode secrets?

What is immutable infrastructure and how does it differ from mutable?

What is DevOps? Is it just a job title or a set of tools?

What is the difference between a container and a virtual machine (VM)?

Why do you need orchestration (Kubernetes) and what problem does it solve?

What is the difference between resource requests and limits in Kubernetes?

What is Helm and what problem does it solve in Kubernetes?

When do you use a Job, a CronJob and a DaemonSet in Kubernetes?

What is the difference between horizontal and vertical scaling?

What is the difference between stateless and stateful applications, and why prefer stateless?

How does Prometheus work — the pull model and metric types?

How do trunk-based development and GitFlow differ?

What is Ansible and how does it differ from Terraform?

What is CIDR notation, and what does `10.0.0.0/16` mean?

What is GitOps and how does it differ from traditional CI/CD deployment?

What is Terraform state, and why do you need remote state and state locking?

What is the difference between SLI, SLO, SLA and an error budget?

How does RBAC work in Kubernetes?

What is distributed tracing, and how do spans and traces differ?

How does the Kubernetes networking model work, and how do pods communicate?

How would you design a CI/CD pipeline for an application?

How do you deploy with zero downtime and roll back quickly when something breaks?

How would you set up monitoring and alerting for a service?

How do you configure nginx as a reverse proxy for a Node/PHP app, and how do virtual hosts work?

A pod is in CrashLoopBackOff or ImagePullBackOff — how do you diagnose it?

A Docker container exits right after starting, or is killed with exit code 137 — how do you debug it?

From typing a URL to the page rendering — what happens?

How do you set up SSL/TLS with Let's Encrypt and certbot — the issuance flow and auto-renewal?

What components make up a Kubernetes cluster?

All DevOps & Cloud Essentials interview questions

Blue-green vs canary deployment — what is the difference?
What is the difference between a Docker image and a container?
What is a Dockerfile and what are the common instructions?
How do Docker layers and the build cache work?
What is a multi-stage build and what problem does it solve?
How do volumes and bind mounts differ, and why are they needed?
What are the Docker network drivers?
What is Docker Compose used for?
How do you reduce Docker image size?
What is a Pod in Kubernetes?
What is the difference between a Deployment and a ReplicaSet?
What is a Kubernetes Service and what types exist?
How does Ingress differ from a LoadBalancer Service?
What is the difference between a ConfigMap and a Secret?
What are Kubernetes namespaces used for?
How does the Horizontal Pod Autoscaler (HPA) work?
What is the difference between liveness and readiness probes?
How do rolling updates and rollbacks work in a Deployment?
How does a StatefulSet differ from a Deployment, and when do you use it?
What is a CI/CD pipeline and what stages does it have?
Distinguish Continuous Integration, Delivery and Deployment.
What is an artifact in CI/CD?
What is Amazon EC2?
What is Amazon S3 and its key characteristics?
What is the difference between an IAM role and an IAM policy?
What is a VPC and what are its components?
How do ALB and NLB differ, and when do you use each?
How does AWS Auto Scaling work?
What is Amazon RDS and its benefit over self-managing a DB on EC2?
What are AWS Lambda and serverless?
What is CloudFront (a CDN) and what problem does it solve?
What is the difference between a Region and an Availability Zone (AZ)?
What is the difference between high availability and fault tolerance?
What is a process in Linux, and how do you inspect/manage it?
What are Linux signals, and how do SIGTERM and SIGKILL differ?
How do you read Linux file permissions, and what does `chmod 755` mean?
What is systemd and what is it used for?
What is cron used for and how do you read a cron schedule?
How do TCP and UDP differ, and when do you use each?
What is the difference between HTTP and HTTPS?
What is DNS and how does name resolution work?
What is load balancing, and how do L4 and L7 differ?
What is the difference between a reverse proxy and a forward proxy?
What is a firewall, and how do security groups differ from Network ACLs?
What is the 12-factor app and some of its key principles?
What is Infrastructure as Code (IaC), and what does Terraform solve?
How do monitoring, logging and observability differ?
What is secrets management, and why not hardcode secrets?
What is immutable infrastructure and how does it differ from mutable?
What is DevOps? Is it just a job title or a set of tools?
What is the difference between a container and a virtual machine (VM)?
Why do you need orchestration (Kubernetes) and what problem does it solve?
What is the difference between resource requests and limits in Kubernetes?
What is Helm and what problem does it solve in Kubernetes?
When do you use a Job, a CronJob and a DaemonSet in Kubernetes?
What is the difference between horizontal and vertical scaling?
What is the difference between stateless and stateful applications, and why prefer stateless?
How does Prometheus work — the pull model and metric types?
How do trunk-based development and GitFlow differ?
What is Ansible and how does it differ from Terraform?
What is CIDR notation, and what does `10.0.0.0/16` mean?
What is GitOps and how does it differ from traditional CI/CD deployment?
What is Terraform state, and why do you need remote state and state locking?
What is the difference between SLI, SLO, SLA and an error budget?
How does RBAC work in Kubernetes?
What is distributed tracing, and how do spans and traces differ?
How does the Kubernetes networking model work, and how do pods communicate?
How would you design a CI/CD pipeline for an application?
How do you deploy with zero downtime and roll back quickly when something breaks?
How would you set up monitoring and alerting for a service?
How do you configure nginx as a reverse proxy for a Node/PHP app, and how do virtual hosts work?
A pod is in CrashLoopBackOff or ImagePullBackOff — how do you diagnose it?
A Docker container exits right after starting, or is killed with exit code 137 — how do you debug it?
From typing a URL to the page rendering — what happens?
How do you set up SSL/TLS with Let's Encrypt and certbot — the issuance flow and auto-renewal?
What components make up a Kubernetes cluster?