30+ Advanced AWS EKS (Elastic Kubernetes Service) Interview Questions and Answers for Experienced Professionals – 2025
Preparing for a senior DevOps, Platform Engineer, or Kubernetes Architect role involving AWS EKS? This comprehensive guide from www.cloudsoftsol.com features over 30 advanced, scenario-based AWS EKS interview questions with detailed answers. Updated for 2025, it covers the latest EKS features including EKS Auto Mode, Karpenter 1.0, Bottlerocket AMIs, EKS Pod Identity, Fargate enhancements, IRSA v2, EKS Blueprints, and integration with AWS services like EKS Anywhere, GuardDuty, and Security Lake.
Questions are organized into modules for easy navigation. Each answer includes real-world scenarios, best practices, troubleshooting tips, and code examples to help you excel in senior-level interviews.
Module: EKS Architecture & Design
- Scenario: Design a highly available, multi-region EKS cluster for a global application with strict data residency requirements. Deploy separate EKS clusters in each region (e.g., us-east-1, eu-west-1). Use EKS Control Plane in the same region as worker nodes. Implement global load balancing with Route 53 and Global Accelerator. Use Amazon EFS with cross-region replication for shared storage. Use AWS Global Accelerator for low-latency traffic routing. Enable EKS Pod Identity for service accounts and cross-account IAM roles for secure access to other AWS services.
- What are the key differences between EKS Managed Node Groups, Self-Managed Node Groups, and Fargate?
- Managed Node Groups: AWS manages the EC2 instances, ASG, and upgrades.
- Self-Managed: Full control over instance types, AMIs, and scaling (ideal for custom AMIs like Bottlerocket).
- Fargate: Serverless compute—no nodes to manage. Best for stateless workloads. In 2025, Fargate supports Graviton processors and GPU workloads.
- Scenario: You need to run both CPU-intensive and GPU-intensive workloads on the same cluster. How would you architect it? Use node selectors, taints/tolerations, and node groups. Create separate managed node groups for CPU (c6i/c7i) and GPU (g5/g6). Use Karpenter for dynamic provisioning. Apply taints to GPU nodes and tolerations to GPU pods. Use EKS Pod Identity to grant GPU pods access to AWS services without long-lived keys.
Module: EKS Security & Identity
- What is EKS Pod Identity (2025) and how does it differ from IRSA? EKS Pod Identity (introduced 2024, GA 2025) is the recommended way to provide AWS IAM permissions to pods. It uses a new OIDC provider per cluster and simplifies role association via annotations. Key advantages over IRSA: No need to create OIDC provider per cluster, no trust policy changes when clusters are recreated, and better performance.
- Scenario: Secure EKS cluster access for multiple teams with least-privilege principles. Use AWS IAM Identity Center (formerly SSO) + EKS RBAC. Map IAM roles to Kubernetes RBAC roles via aws-auth ConfigMap (legacy) or EKS Access Entries (recommended). Use EKS Pod Identity for workload IAM. Enable Amazon GuardDuty for EKS protection and AWS Security Lake for centralized security data.
- How do you enable private cluster access while allowing public endpoint for kubectl? Enable private endpoint only. Use AWS PrivateLink or VPC endpoints for control plane access. For external kubectl, use AWS Systems Manager Session Manager or bastion hosts in the same VPC.
Module: Scaling & Autoscaling
- Scenario: Implement cost-effective, fast autoscaling for variable workloads. Use Karpenter 1.0 (preferred over Cluster Autoscaler). Karpenter provisions nodes in seconds based on pod scheduling needs. Combine with Spot Instances and Savings Plans. Enable EKS Auto Mode (2025) for fully managed scaling, networking, and storage.
- What is EKS Auto Mode and when should you use it? EKS Auto Mode (preview 2025) fully automates cluster management: node provisioning, scaling, networking, and storage. Ideal for teams that want a managed Kubernetes experience similar to Google Kubernetes Engine (GKE) Autopilot. Use it for new clusters where operational overhead must be minimal.
- Scenario: You have bursty workloads that sometimes require hundreds of nodes. How do you optimize costs? Use Karpenter with Spot Instances (up to 90% savings). Set up multiple provisioners with different instance types and capacity types. Use karpenter.sh/capacity-type: spot and fallback to on-demand. Enable consolidation to reduce fragmentation.
Module: Networking & Service Mesh
- What is the difference between Amazon VPC CNI, Calico, and Cilium?
- Amazon VPC CNI: Native AWS integration, secondary IP mode, best performance.
- Calico: Supports network policies and IPAM.
- Cilium: eBPF-based, advanced observability, Hubble UI, and security features. Use Cilium for advanced network policies and observability.
- Scenario: Implement service mesh with observability and traffic management. Use AWS App Mesh or Istio with Amazon EKS. For managed experience, use Amazon EKS Blueprints with AWS Load Balancer Controller + Istio. Enable AWS X-Ray for tracing and CloudWatch Container Insights for metrics.
Module: Storage & Data Management
- How do you provide persistent storage for stateful applications on EKS? Use Amazon EBS CSI Driver for block storage, EFS CSI Driver for shared file systems, and Amazon FSx for Lustre/NetApp ONTAP for high-performance workloads. Use StorageClass with volumeBindingMode: WaitForFirstConsumer.
- Scenario: You need to migrate stateful workloads (PostgreSQL) from on-premises to EKS without downtime. Use Amazon EKS with Amazon RDS or Amazon Aurora PostgreSQL. For self-managed, use StatefulSet + EBS volumes. Perform live replication using pglogical or AWS DMS, then cut over DNS.
Module: CI/CD & GitOps
- Scenario: Implement GitOps for EKS using ArgoCD or Flux. Use ArgoCD with EKS IAM roles for Git access. Store manifests in Git, use Helm charts for applications. Enable self-healing and auto-sync. Use ArgoCD ApplicationSets for multi-cluster management.
- How do you manage Helm charts and secrets securely? Use Helm with external-secrets operator or AWS Secrets Manager + External Secrets operator. Store sensitive values in Secrets Manager or Parameter Store. Use Sealed Secrets for Git-based secret management.
Module: Monitoring, Logging & Observability
- What is the recommended observability stack for EKS in 2025? Amazon CloudWatch Container Insights + AWS X-Ray + Amazon Managed Grafana + Amazon Managed Prometheus. Use AWS Distro for OpenTelemetry (ADOT) for collection.
- Scenario: You need to troubleshoot high CPU usage in a pod. Use CloudWatch Container Insights, kubectl top, and Prometheus metrics. Check for memory leaks with kubectl exec and tools like htop. Use AWS X-Ray for distributed tracing.
Module: Upgrades & Maintenance
- How do you perform zero-downtime EKS control plane upgrades? EKS control plane upgrades are zero-downtime by design (AWS manages it). For node upgrades, use managed node group rolling updates or Karpenter with drift detection.
- Scenario: Plan a major Kubernetes version upgrade (1.29 → 1.30). Check deprecated APIs with kubectl convert. Use eksctl upgrade cluster or AWS Console. Test in staging first. Use EKS Add-ons version compatibility matrix.
Module: Advanced & Scenario-Based Questions
- Scenario: Run machine learning workloads on EKS with GPU and Inferentia. Use Neuron devices (Inferentia/Trainium) with AWS Neuron SDK. Deploy via EKS managed node groups with Inf1/Trn1 instances. Use Kubeflow or SageMaker on EKS for orchestration.
- How do you implement multi-tenancy on a single EKS cluster? Use namespaces with resource quotas, network policies, and RBAC. Use AWS IAM roles per namespace via EKS Pod Identity. Consider Karpenter provisioners per tenant.
- What is EKS Anywhere and when should you use it? EKS Anywhere brings EKS to on-premises or edge environments. Use it for air-gapped or hybrid scenarios where cloud is not possible.
- Scenario: Implement disaster recovery for EKS. Use Velero with Amazon S3 for backups. Replicate control plane configuration via Terraform. Use EKS Blueprints for consistent cluster recreation.
- How do you secure container images in EKS? Use Amazon ECR with image scanning (Clair). Enforce image signing with cosign or notary. Use admission controllers like Gatekeeper or Kyverno to block unsigned images.
- Scenario: You need to run Windows containers on EKS. Use Windows managed node groups with Windows Server 2022 AMIs. Deploy Windows workloads with nodeSelector and tolerations.
For more AWS EKS training, certification prep (AWS Certified DevOps Engineer, AWS Certified Solutions Architect – Professional), hands-on labs, and enterprise Kubernetes solutions, visit www.cloudsoftsol.com. Stay ahead in your AWS and Kubernetes career with our expert resources!
