DevOps Graduate Trainee Interview Flashcards

A complete revision flashcard set designed for a DevOps Graduate Trainee interview covering Kubernetes, Linux/Bash, networking, Docker, CI/CD, observability, troubleshooting, systems design, and cloud fundamentals.

What is DevOps?

DevOps is a combination of practices, tools, and culture that brings development and operations closer together to make building, deploying, and maintaining software more reliable and efficient through automation, CI/CD, infrastructure as code, monitoring, and continuous feedback.

What does a normal day look like for a DevOps engineer?

A DevOps engineer monitors infrastructure and applications, checks deployment pipelines, troubleshoots incidents, works with developers to resolve issues, and automates repetitive processes to make deployments reliable and systems scalable.

What is Kubernetes?

Kubernetes is a container orchestration platform used to deploy, manage, scale, and maintain containerized applications by automating scheduling, restarting failed workloads, scaling, service discovery, and rolling updates.

What is a Pod in Kubernetes?

A Pod is the smallest deployable unit in Kubernetes. It usually contains one container, but related containers can share a Pod's network and storage context.

What is a Deployment in Kubernetes?

A Deployment manages the desired state of an application through ReplicaSets and Pods, supporting declarative updates, scaling, and rolling updates.

What is a Service in Kubernetes?

A Service provides a stable network endpoint for a group of Pods because Pod IP addresses can change when Pods are replaced.

What is the difference between a ConfigMap and a Secret in Kubernetes?

A ConfigMap stores non-sensitive configuration, whereas a Secret stores sensitive configuration such as passwords, API keys, and tokens.

What is a Namespace in Kubernetes?

A Namespace provides logical isolation and organization of Kubernetes resources within a cluster.

What is Ingress in Kubernetes?

Ingress provides HTTP/HTTPS routing from outside the cluster to Services, commonly based on hostnames or URL paths, through an Ingress Controller.

What are the main components of the Kubernetes control plane?

The API Server (main entry point), Scheduler (chooses nodes for Pods), Controller Manager (maintains desired state), and etcd (stores cluster state).

What is the role of the kubelet in Kubernetes?

The kubelet is an agent on each worker node that helps ensure the containers described by Pods are running as expected.

What is the difference between readiness, liveness, and startup probes?

Readiness checks whether a Pod should receive traffic; liveness checks whether a container should continue running or be restarted; startup gives slow-starting applications time to initialize before liveness checks begin.

What is the Horizontal Pod Autoscaler (HPA)?

HPA automatically adjusts the number of Pod replicas based on resource or custom metrics.

What is the memory aid for pre-deployment checks in Kubernetes?

IMAGE → RESOURCES → NETWORK → CONFIG → SECURITY → HEALTH → SCALE → MONITOR

What do common Pod states Pending, Running, CrashLoopBackOff, and ImagePullBackOff mean?

Pending: not yet scheduled/started. Running: started, but not necessarily healthy. CrashLoopBackOff: repeatedly crashing with restart backoff. ImagePullBackOff: image cannot be pulled and Kubernetes is retrying.

How do you troubleshoot a failing Pod in Kubernetes?

Start with status and events, then inspect the Pod, logs, image/configuration, resources, and dependencies using commands such as kubectl get pods, kubectl describe pod, kubectl logs, and kubectl get events.

What is the recommended health-check approach for a Linux server?

Follow the order: system overview → CPU → memory → disk → processes → networking → services → logs.

Which Linux commands are used to check memory, disk, listening ports, and services?

Memory: free -h; Disk: df -h; Listening ports: ss -tulpn; Services: systemctl status.

What is SSH and what is its default port?

SSH (Secure Shell) is commonly used to remotely connect to Linux servers, typically operating on port 22.

What is DNS and what is the lookup flow for a web request?

DNS (Domain Name System) translates domain names into IP addresses. Flow: www.example.com → DNS lookup → IP address → server connection → HTTP/HTTPS request.

How do HTTP and HTTPS differ in terms of ports and security?

HTTP uses port 80 and does not encrypt application traffic; HTTPS uses port 443 and protects HTTP traffic using TLS for confidentiality, integrity protection, and server authentication.

What is TCP?

TCP is a connection-oriented transport protocol that provides reliable, ordered delivery of data.

What is a load balancer?

A load balancer distributes incoming traffic across backend instances or servers, improving scalability, availability, and performance.

What is a container?

A container is an isolated application process packaged with its dependencies that shares the host operating system kernel.

What is the difference between a Dockerfile and Docker Compose?

A Dockerfile defines instructions for building a single Docker image, while Docker Compose defines and manages one or more related containers and services together.

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

An image is the package/template; a container is a running instance of an image.

What is the typical flow of a CI/CD pipeline for a Java application?

Java code → Git push → CI → Build → Test → JAR → Docker image (optional) → Registry → Deploy → Health checks → Monitoring.

What is the difference between CI and CD?

CI (Continuous Integration) automatically builds and tests integrated code changes; CD (Continuous Delivery/Deployment) automates the delivery and/or deployment of validated changes.

What is observability and what are its three major signals?

Observability is the ability to understand a system's internal behavior from its outputs. Its three major signals are logs (what happened?), metrics (how is it performing?), and traces (where did the request spend time?).

What components form a complete Kubernetes observability architecture?

Fluent Bit (log collection), Loki or Elasticsearch/OpenSearch (log storage), Prometheus (metrics collection), Node Exporter and kube-state-metrics (node/k8s metrics), Grafana (visualization), Alertmanager (notifications), and OpenTelemetry with Jaeger or Tempo (tracing).

What troubleshooting framework should be used if a service is slow?

Metrics → Logs → Dependencies → Infrastructure → Fix → Verify.

What action should you take if CPU utilization reaches 95%?

Investigate why CPU is high first (e.g., traffic, inefficient code, runaway processes, or resource limits) rather than immediately scaling up CPU, because scaling does not replace root-cause analysis.

What is a rollback?

Returning an application or deployment to a previously known-good version after a problematic change.

What is the difference between horizontal and vertical scaling?

Horizontal scaling adds more instances/replicas; vertical scaling increases the CPU or memory of an existing instance.

What is a stateless application?

An application that does not depend on local instance memory to retain state between requests, relying instead on shared systems like databases or caches.

What is the difference between an AWS Region and an Availability Zone?

An AWS Region is a geographic area containing multiple isolated Availability Zones, while an Availability Zone is an isolated location within a Region.

What is Infrastructure as Code (IaC) and what tool is commonly used?

IaC means defining infrastructure in version-controlled configuration so environments can be created consistently and automated; Terraform is a common IaC tool.

What is the cloud shared responsibility model?

The provider is responsible for security OF the cloud; the customer is responsible for security IN the cloud.

How should you handle a deployment failure disagreement with a developer?

Remain calm, focus on resolving the technical issue rather than assigning blame, investigate using logs/metrics, suggest rolling back if necessary to restore service, and document and prevent recurrence collaboratively.

What is the recommended graduate trainee interview answer structure?

Understand the problem → gather evidence → make a controlled change → verify → document → prevent recurrence.