Amazon EKS has become a popular choice for running containerized workloads securely and at scale using Kubernetes. As companies shift towards microservices, managing networking, observability, node hardening, and scaling within EKS becomes crucial. These topics frequently appear in cloud and DevOps interviews because they reflect real-world operational challenges.
This blog focuses on the most relevant EKS interview questions and answers related to service mesh, ingress, EKS security, node hardening, and cluster scaling. The goal is to give you clear explanations that help you confidently discuss Kubernetes in AWS during your interviews.
EKS Interview Questions and Answers
Question 1. What is a service mesh in EKS?
Answer: A service mesh adds a dedicated communication layer for microservices, providing traffic control, metrics, encryption, and security without changing application code. In EKS, tools like Istio and AWS App Mesh are commonly used for service-to-service communication with added observability and policy enforcement.
Question 2. What are the benefits of using a service mesh in EKS?
Answer:
- Mutual TLS for secure traffic inside the cluster
- Retries and circuit-breaking for resilience
- Fine-grained traffic routing for deployments
- Centralized telemetry and service-level insights
- Uniform policy enforcement for all microservices
Question 3. How does App Mesh integrate with EKS?
Answer: App Mesh uses sidecar proxies (often Envoy) injected into pods. These proxies handle traffic routing, encryption, and monitoring. It centrally manages service communication across EKS clusters and even hybrid or multi-environment setups.
Question 4. What is an Ingress in Kubernetes?
Answer: Ingress manages external access to services within the cluster. It acts as an entry point, allowing routing based on hostnames or paths. In EKS, implementations like AWS Load Balancer Controller integrate with ALB or NLB for scalable routing.
Question 5. What is the AWS Load Balancer Controller?
Answer: It automatically provisions and configures AWS load balancers like ALB or NLB for EKS. It reads Kubernetes Ingress and Service specifications, generating cloud resources based on your routing logic and traffic requirements.
Question 6. What is node hardening in EKS?
Answer: Node hardening refers to securing worker nodes by:
- Using least privilege IAM roles
- Enforcing patching and OS updates
- Enabling encryption and secure SSH access
- Restricting root privileges and container capabilities
- Scanning images for vulnerabilities
This improves overall EKS security and reduces runtime risks.
Question 7. How do you secure IAM permissions for EKS workloads?
Answer: By using IAM roles for service accounts (IRSA). This approach attaches IAM permissions to Kubernetes service accounts instead of EC2 nodes, ensuring precise access control for workloads.
Question 8. How does the Cluster Autoscaler work?
Answer: If pods cannot be scheduled because of insufficient resources, it adds new worker nodes. When nodes are under-utilized, it may remove them to save cost. It directly interacts with AWS Auto Scaling groups.
Question 9. What is Karpenter and how is it different from Cluster Autoscaler?
Answer: Karpenter is a high-performance open-source autoscaler from AWS. While Cluster Autoscaler relies on scaling groups, Karpenter provisions EC2 instances directly and faster. It supports diverse instance types, improving cost optimization and flexibility for scaling.
Question 10. What are Pod Security Standards (PSS) in EKS?
Answer: PSS is Kubernetes-native security that enforces restrictions on pod behavior such as privilege level, host access, or volume mounts. It helps ensure pods follow safe execution practices.
Question 11. How do you monitor EKS workloads?
Answer: Using:
- Amazon CloudWatch Container Insights
- Kubernetes Metrics Server
- Prometheus and Grafana for observability
- CloudTrail for auditing administrative events
Monitoring supports scaling decisions and security threat detection.
Question 12. Why is node isolation important for EKS?
Answer: Node isolation ensures workloads with different security requirements do not run on shared compute. It can be achieved using taints, tolerations, and dedicated node groups, improving security and regulatory compliance.
Question 13. Why use a service mesh for zero-trust networking?
Answer: Because it enforces mutual TLS and authentication between every service call, preventing lateral attacks and ensuring secure communication inside the cluster.
Question 14. What is mutual TLS (mTLS) and why is it important?
Answer: mTLS validates both the client and server during traffic exchanges. It encrypts traffic within the cluster and ensures communication only between verified services, improving overall EKS security posture.
Question 15. How does ingress help with canary deployments?
Answer: Ingress controllers support weighted routing, where only a portion of the traffic goes to a new version of a service. This allows safely testing changes in real user environments.
Conclusion
EKS enables organizations to securely run containers at scale while supporting flexible networking, modern microservice communication, and strong EKS security practices. By learning about service mesh, ingress controllers, node hardening, and scaling automation, you can confidently design robust Kubernetes solutions in AWS. These interview questions give you the foundation to discuss real-world scenarios and operational best practices that hiring teams look for.
Keep exploring hands-on deployments to reinforce these concepts and stay adaptable to evolving Kubernetes capabilities.
