AWS Interview Questions and Answers

These are foundational questions for beginners or freshers.

1. What is AWS?

Answer:
AWS (Amazon Web Services) is a cloud computing platform by Amazon that provides on-demand infrastructure services such as computing power, storage, databases, networking, and security.

2. What are the main components of AWS?

Answer:

• Compute Services: EC2, Lambda, ECS, EKS
• Storage Services: S3, EBS, EFS
• Database Services: RDS, DynamoDB, Aurora
• Networking: VPC, Route 53, ELB, CloudFront
• Security & Identity: IAM, AWS Shield, KMS

3. What is EC2 in AWS?

Answer:
Amazon Elastic Compute Cloud (EC2) is a scalable virtual server that allows users to run applications on AWS infrastructure. It provides different instance types optimized for compute, memory, and storage.

4. What is S3 in AWS?

Answer:
Amazon Simple Storage Service (S3) is an object storage service that offers high availability, scalability, and security for storing data in buckets.

5. What is an IAM role in AWS?

Answer:
IAM (Identity and Access Management) roles allow AWS services or users to access resources securely without requiring long-term credentials.

6. What is an AWS Region and Availability Zone?

Answer:

• Region: A geographic area with multiple data centers (e.g., us-east-1, ap-south-1).
• Availability Zone (AZ): A separate data center within a region to ensure fault tolerance.

7. What is an Elastic Load Balancer (ELB)?

Answer:
ELB distributes incoming traffic across multiple EC2 instances to ensure high availability and fault tolerance.

8. What is AWS Lambda?

Answer:
AWS Lambda is a serverless compute service that runs code in response to events without provisioning or managing servers.

9. What is an Auto Scaling Group (ASG)?

Answer:
Auto Scaling dynamically adjusts the number of EC2 instances based on demand to ensure high availability.

10. What is a VPC in AWS?

These are for professionals with some AWS experience.

11. What is the difference between EBS and EFS?

Answer:

• EBS (Elastic Block Store): Block storage for EC2 instances, supports snapshots, and requires mounting to a single instance.
• EFS (Elastic File System): Managed file storage that supports multiple EC2 instances simultaneously.

12. How does AWS Route 53 work?

Answer:
AWS Route 53 is a scalable DNS web service that routes end users to AWS services or external domains based on routing policies like weighted, latency-based, and geolocation-based routing.

13. How does AWS CloudFormation work?

Answer:
AWS CloudFormation automates infrastructure deployment using templates written in YAML or JSON.

14. What is AWS SNS and SQS?

Answer:

• SNS (Simple Notification Service): Pub/Sub messaging for notifications.
• SQS (Simple Queue Service): Message queuing service for decoupling microservices.

15. How does AWS CloudWatch differ from AWS CloudTrail?

Answer:

• CloudWatch: Monitors AWS resources and applications in real-time.
• CloudTrail: Logs AWS API calls for auditing and compliance.

16. What are AWS Organizations?

Answer:
AWS Organizations is a service that helps manage multiple AWS accounts under a single organization for consolidated billing and security.

17. What is a NAT Gateway, and why is it used?

Answer:
A NAT (Network Address Translation) Gateway allows private subnet instances to access the internet while preventing inbound traffic.

18. What is AWS WAF?

These questions are for experienced AWS professionals and architects.

19. How does AWS Direct Connect work?

Answer:
AWS Direct Connect provides a dedicated network connection from an on-premise data center to AWS, reducing latency and increasing bandwidth.

20. What is Amazon EKS and how does it work?

Answer:
Amazon Elastic Kubernetes Service (EKS) is a managed Kubernetes service that runs Kubernetes clusters on AWS.

21. How do you secure an S3 bucket?

Answer:

• Use IAM policies to restrict access
• Enable S3 bucket policies
• Use AWS KMS for encryption
• Enable S3 Block Public Access
• Enable Versioning and Logging

22. What is AWS Transit Gateway?

Answer:
AWS Transit Gateway simplifies network connectivity between multiple VPCs and on-premises networks.28. What are the different AWS Storage Gateway types?

Answer:

• File Gateway: Stores files as objects in S3
• Volume Gateway: Uses block storage with snapshots in S3
• Tape Gateway: Virtual tape library for backup

23. What is the difference between AWS Fargate and ECS?

Answer:

• Fargate: Serverless container management where AWS handles infrastructure
• ECS: Container orchestration where users manage EC2-based container instances

24. How does AWS Control Tower work?

Answer:
AWS Control Tower simplifies multi-account governance and enforces security best practices across AWS environments.