EKS interview question · Most asked
What is Amazon EKS, and what does AWS manage versus what do you manage?
Summary
EKS is AWS's managed Kubernetes service. AWS runs and scales the control plane (API servers and etcd across multiple Availability Zones), patches it, and backs up etcd. You manage the worker capacity (unless you use Fargate or EKS Auto Mode), add-ons, networking design, IAM, workloads, upgrades of node versions, and everything running in the cluster.
Longer Answer
The control plane runs in an AWS-managed account and connects to your VPC through elastic network interfaces; the API endpoint can be public, private or both. You pay a per-cluster hourly fee (higher for versions in extended support) plus the compute, load balancers, storage and data transfer you use.
Shared responsibility shifts with the compute option: with self-managed nodes you own the OS and kubelet; with managed node groups AWS automates provisioning and updates you trigger; with Fargate or Auto Mode AWS manages more of the node lifecycle.
Key Points
- AWS manages the multi-AZ control plane and etcd.
- You manage nodes (unless Fargate/Auto Mode), add-ons, IAM, workloads.
- Per-cluster fee plus resources.
- Responsibility depends on compute option.
Explanation
What interviewers look for
Clear understanding of the shared responsibility split and its cost model.
More most-asked EKS questions
- How do you secure an EKS cluster end to end?
- EKS or ECS: how would you choose?
- IRSA or EKS Pod Identity: how do pods get AWS permissions?
- How does the Amazon VPC CNI work, and why do EKS clusters run out of IP addresses?
- How do you expose services on EKS? Explain the AWS Load Balancer Controller.
- How do you upgrade an EKS cluster, and what are standard and extended support?
- Why is Karpenter popular on EKS, and how does it differ from the Cluster Autoscaler?
- Compare the EKS compute options: managed node groups, self-managed nodes, Fargate, Karpenter and EKS Auto Mode.