Interview › Kubernetes, Docker, Helm & Podman
What are Kubernetes QoS classes (Guaranteed, Burstable, BestEffort)?
Kubernetes, Docker, Helm & Podman · Intermediate level
Answer
Kubernetes QoS classes are Guaranteed, Burstable, and BestEffort. They are derived from requests and limits and affect eviction priority when a node is under resource pressure.
Technical explanation
Guaranteed requires every container to have equal CPU and memory request and limit.
BestEffort Pods have no requests or limits and are first candidates for eviction under pressure.
Troubleshooting starts from state and events: get, describe, logs, previous logs, events, and then node/runtime/network checks.
Separate scheduling failures, image pull failures, runtime failures, app failures, and traffic-routing failures so you do not fix the wrong layer.
Operational commands like drain and rollback must respect PDBs, probes, and workload disruption tolerance.
Hands-on example
1. In a non-production namespace, create this safe broken scenario: create Guaranteed, Burstable, and BestEffort Pods and inspect QoSClass.
2. Follow a fixed triage order: kubectl get, describe, logs or logs --previous, events, rollout status, node status, and then runtime/network checks.
3. Fix only one variable at a time so the root cause is clear rather than accidentally masked.
4. Save the commands and final diagnosis as an interview-ready incident walkthrough.
Check how well your resume matches the role with our free resume checker— match score, ATS check, and the skills you're missing.
More Kubernetes, Docker, Helm & Podman interview questions
- What is Kubernetes, and what problem does it solve over running containers manually?
- Explain the Kubernetes control plane components (API server, etcd, scheduler, controller manager).
- What runs on a worker node (kubelet, kube-proxy, container runtime)?
- What is a Pod, and why does Kubernetes schedule Pods rather than containers?
- What is the difference between a Pod, a ReplicaSet, and a Deployment?
- How does a Deployment perform a rolling update, and how do maxSurge and maxUnavailable work?
- How do you roll back a Deployment, and how does Kubernetes track revisions?
- What is a Service, and what are the types (ClusterIP, NodePort, LoadBalancer, ExternalName)?