For AI Architect, Cloud Architect, DevOps, Platform Engineering, and AWS Solution Architect interviews, Amazon EKS is one of the most frequently asked topics.

1. What is Amazon EKS?

Answer

Amazon EKS (Amazon Elastic Kubernetes Service (EKS)) is a fully managed Kubernetes service provided by Amazon Web Services (AWS).

It eliminates the need to manage Kubernetes control plane components such as:

API Server
etcd
Scheduler
Controller Manager

AWS manages:

Kubernetes control plane
High availability
Security patches
Upgrades

Customers manage:

Worker nodes
Applications
Networking policies
Storage

2. Why use EKS instead of self-managed Kubernetes?

Answer

Self Managed Kubernetes	Amazon EKS
Manage masters	AWS manages masters
Manual upgrades	Managed upgrades
etcd maintenance	AWS maintains etcd
HA setup required	Built-in HA
Higher operational effort	Reduced effort

Benefits

Managed Kubernetes
High availability
Security
Integration with AWS services
Scalability

3. Explain EKS Architecture.

Answer

EKS architecture consists of:

Control Plane (AWS Managed)

Components:

API Server
Scheduler
Controller Manager
etcd

AWS runs control plane across multiple Availability Zones.

Data Plane (Customer Managed)

Worker Nodes:

EC2 instances
Fargate

Applications run here.

Flow

User → kubectl → API Server → Scheduler → Worker Nodes

4. What components are managed by AWS in EKS?

Answer

AWS manages:

Kubernetes API Server
etcd
Scheduler
Controller Manager
Control plane upgrades
High Availability

Customer manages:

Worker nodes
Containers
Deployments
Services
Storage

5. What is a Kubernetes Cluster?

Answer

A cluster consists of:

Control Plane

Manages cluster state.

Worker Nodes

Run application pods.

Example:

EKS Cluster
|
|-- Control Plane
|
|-- Node Group
      |
      |-- Node1
      |-- Node2
      |-- Node3

6. What is a Node Group in EKS?

Answer

A Node Group is a collection of EC2 instances that run Kubernetes workloads.

Types:

Managed Node Group

AWS manages:

Provisioning
Upgrades
Scaling

Self-Managed Node Group

Customer manages everything.

Managed Node Groups are preferred.

7. What are Managed Node Groups?

Answer

AWS-managed worker nodes.

Benefits:

Auto Scaling integration
Easier upgrades
Health monitoring
Reduced operational burden

8. What is Self-Managed Node Group?

Answer

Customer provisions EC2 instances manually.

Responsibilities:

AMI updates
Patching
Scaling
Lifecycle management

Used when custom requirements exist.

9. What is EKS Fargate?

Answer

EKS Fargate allows running pods without managing EC2 servers.

AWS automatically:

Provisions compute
Scales infrastructure
Patches OS

Benefits:

Serverless Kubernetes
Reduced operational overhead

10. EKS on EC2 vs EKS on Fargate

Feature	EC2	Fargate
Node Management	Required	No
Cost Control	Better	Higher
Flexibility	High	Medium
Operations	More	Less
Serverless	No	Yes

11. What is kubelet?

Answer

Kubelet is an agent running on every worker node.

Responsibilities:

Registers node
Monitors pods
Reports status
Communicates with API Server

12. What is kubectl?

Answer

kubectl is Kubernetes CLI.

Examples:

Get pods:

kubectl get pods

Get nodes:

kubectl get nodes

Deploy application:

kubectl apply -f deployment.yaml

13. How does EKS authenticate users?

Answer

Authentication uses:

AWS IAM

Users authenticate using IAM credentials.

Authorization occurs via:

aws-auth ConfigMap (legacy)
EKS Access Entries (recommended)

14. Explain IAM Roles for Service Accounts (IRSA).

Answer

IRSA allows Kubernetes pods to assume IAM roles directly.

Without IRSA:

Pod
 ↓
Node IAM Role

With IRSA:

Pod
 ↓
Dedicated IAM Role

Benefits:

Least privilege
Improved security

Common interview question.

15. What is OIDC in EKS?

Answer

OpenID Connect enables:

IRSA
Pod-level IAM access

EKS creates OIDC provider.

Pods receive temporary AWS credentials.

16. Explain EKS Networking.

Answer

EKS uses:

VPC

Cluster runs inside AWS VPC.

ENI

Elastic Network Interfaces attached to worker nodes.

Pod Networking

Each pod receives IP address from VPC.

17. What is Amazon VPC CNI?

Answer

AWS VPC CNI plugin provides networking.

Features:

Native VPC networking
Pod gets VPC IP
High performance

Default networking plugin in EKS.

18. What is CoreDNS?

Answer

Provides DNS services inside cluster.

Example:

my-service.default.svc.cluster.local

Pods use CoreDNS for service discovery.

19. What is kube-proxy?

Answer

Handles networking rules.

Responsibilities:

Service routing
Load balancing
Traffic forwarding

20. What is a Pod?

Answer

Smallest deployable unit in Kubernetes.

Contains:

One or more containers
Shared network
Shared storage

Example:

Pod
 ├─ App Container
 └─ Sidecar Container

21. What is a Deployment?

Answer

Deployment manages:

Replica creation
Rolling updates
Rollbacks

Example:

replicas: 3

Ensures desired pod count.

22. What is a Service?

Answer

Provides stable endpoint for pods.

Types:

ClusterIP

Internal communication

NodePort

Exposes application externally

LoadBalancer

Creates AWS ELB automatically

23. How does EKS integrate with Load Balancers?

Answer

Using:

AWS Load Balancer Controller

Creates:

Automatically from Kubernetes resources.

24. What is AWS Load Balancer Controller?

Answer

Kubernetes controller that provisions:

Application Load Balancer
Network Load Balancer

Based on Ingress or Service definitions.

25. Explain Ingress.

Answer

Ingress manages HTTP/HTTPS routing.

Example:

api.company.com → API Service
app.company.com → Web Service

Implemented via ALB in AWS.

26. What is Cluster Autoscaler?

Answer

Automatically adds/removes worker nodes.

Triggers:

Pending Pods
Underutilized Nodes

Benefits:

Cost optimization
Scalability

27. What is Karpenter?

Answer

Modern Kubernetes autoscaling solution from AWS.

Advantages over Cluster Autoscaler:

Faster scaling
Better bin packing
Lower cost
Intelligent provisioning

Frequently asked in 2025–2026 interviews.

28. Cluster Autoscaler vs Karpenter

Feature	Cluster Autoscaler	Karpenter
Speed	Moderate	Fast
Provisioning	Node Groups	Dynamic
Cost Optimization	Good	Better
Flexibility	Medium	High

29. How do you secure EKS?

Answer

Best practices:

IRSA
RBAC
Private API Endpoint
Security Groups
Secrets Manager
KMS Encryption
Network Policies
Image Scanning

30. How are secrets managed in EKS?

Answer

Options:

Kubernetes Secrets

Base64 encoded

AWS Secrets Manager

Preferred

Parameter Store

Alternative solution

31. How does EKS support High Availability?

Answer

Control Plane:

Multi-AZ

Worker Nodes:

Multiple AZs
Auto Scaling

Load Balancers:

Multi-AZ

Result:

No single point of failure.

32. Explain EKS Upgrade Process.

Answer

Steps:

Upgrade control plane
Upgrade add-ons
Upgrade worker nodes
Validate workloads

Best practice:

Upgrade one version at a time.

33. How do you monitor EKS?

Answer

Tools:

Amazon CloudWatch
Prometheus
Grafana
Fluent Bit
Container Insights

Monitor:

CPU
Memory
Pod health
Node health

34. How do you log EKS workloads?

Answer

Common architecture:

Pods
 ↓
Fluent Bit
 ↓
CloudWatch Logs

Alternative:

ELK
OpenSearch

35. Explain EKS Multi-Tenancy.

Answer

Achieved using:

Namespaces
RBAC
Network Policies
Resource Quotas

Provides workload isolation.

36. What is GitOps in EKS?

Answer

Infrastructure and deployments managed via Git.

Tools:

Argo CD
Flux CD

Benefits:

Version control
Auditing
Rollbacks

37. Explain Blue-Green Deployment in EKS.

Answer

Two environments:

Blue → Current
Green → New

Traffic switched after validation.

Advantages:

Zero downtime
Easy rollback

38. Explain Canary Deployment.

Answer

Traffic gradually shifted:

Version A → 90%
Version B → 10%

Monitor before full rollout.

39. What are common EKS interview troubleshooting questions?

Pod Pending

Possible causes:

Insufficient CPU
Insufficient memory
Node unavailable

Check:

kubectl describe pod

ImagePullBackOff

Causes:

Invalid image
Registry permissions

Check:

kubectl describe pod

CrashLoopBackOff

Causes:

App failure
Wrong configuration

Check:

kubectl logs pod-name

40. EKS Architect Interview Scenario

Question

Design a highly available GenAI platform on EKS.

Sample Answer

Architecture:

EKS Multi-AZ
Karpenter Autoscaling
Amazon Bedrock integration
IRSA for AWS access
ALB Ingress
CloudWatch monitoring
GitOps using ArgoCD
Secrets Manager
Private Subnets
ECR for images

Benefits:

Secure
Highly available
Scalable
Cost optimized
Enterprise ready