Prepare for your next AWS interview with these 30 essential questions covering EC2, S3, VPC, Lambda, and more. This guide progresses from basic concepts for freshers to advanced scenarios for experienced professionals with 3-6 years of experience. Each answer is concise, practical, and ready to help you succeed at companies like Atlassian or Zoho.
Basic AWS Interview Questions (Freshers & 1-3 Years Experience)
1. What is AWS and what are its key features?
AWS is Amazon Web Services, a cloud computing platform providing on-demand services like compute, storage, and databases. Key features include scalability, high availability, security via IAM, and pay-as-you-go pricing.
2. What are the three basic types of cloud services in AWS?
The three types are Infrastructure as a Service (IaaS) like EC2, Platform as a Service (PaaS) like Elastic Beanstalk, and Software as a Service (SaaS) like Amazon Chime.
3. Explain Amazon EC2 and its instance types.
Amazon EC2 is Elastic Compute Cloud, providing resizable virtual servers. Instance types include General Purpose (t3), Compute Optimized (c5), Memory Optimized (r5), and Storage Optimized (i3).
4. What is Amazon S3 and what are its storage classes?
Amazon S3 is Simple Storage Service for object storage. Storage classes include Standard, Intelligent-Tiering, Glacier for infrequent access, and Glacier Deep Archive for long-term storage.
5. What is a VPC in AWS?
Virtual Private Cloud (VPC) is a logically isolated network section in AWS where you launch resources. It allows custom IP ranges, subnets, route tables, and internet gateways.
6. What is IAM in AWS?
Identity and Access Management (IAM) manages access to AWS services securely. It uses users, groups, roles, and policies to control permissions.
7. Differentiate between stopping and terminating an EC2 instance.
Stopping an EC2 instance releases compute capacity but preserves the EBS root volume. Terminating deletes the instance and optionally the attached volumes.
8. What is Amazon CloudWatch?
CloudWatch is a monitoring service for AWS resources and applications. It collects metrics, logs, and sets alarms for CPU utilization, storage, etc.
9. What are Security Groups in AWS?
Security Groups act as virtual firewalls for EC2 instances, controlling inbound and outbound traffic. They are stateful, denying all inbound by default and allowing all outbound.
10. What is an Elastic Load Balancer (ELB)?
ELB distributes incoming traffic across multiple targets like EC2 instances for high availability. Types include Application Load Balancer (ALB), Network Load Balancer (NLB), and Gateway Load Balancer (GWLB).
Intermediate AWS Interview Questions (1-3 Years Experience)
11. What are AWS Regions and Availability Zones?
Regions are geographic areas like us-east-1. Availability Zones (AZs) are isolated locations within a region, providing fault tolerance if one AZ fails.
12. Explain NAT Gateway vs NAT Instance.
NAT Gateway is a managed service for outbound internet access from private subnets, highly available and scalable. NAT Instance is a user-managed EC2 instance for the same purpose but requires maintenance.
13. How does Auto Scaling work in AWS?
Auto Scaling adjusts EC2 capacity based on demand using scaling policies like CPU utilization thresholds. It launches or terminates instances in an Auto Scaling Group across AZs.
14. What is Amazon RDS?
RDS is Relational Database Service, a managed database for engines like MySQL, PostgreSQL. It handles backups, patching, Multi-AZ for high availability, and read replicas.
15. Describe AWS Lambda.
AWS Lambda is a serverless compute service running code in response to events without provisioning servers. It supports languages like Python, Node.js, with 15-minute execution limits.
16. What is Amazon EBS and how is it different from EFS?
EBS is block storage for EC2 instances, like virtual disks with snapshots. EFS is elastic file storage for multiple EC2 instances, using NFS protocol.
17. How do you secure data in S3?
Secure S3 with bucket policies, IAM policies, server-side encryption (SSE-S3, SSE-KMS), access control lists, and versioning for data protection.
18. What is AWS CloudFormation?
CloudFormation is Infrastructure as Code (IaC) service using templates (JSON/YAML) to provision and manage AWS resources predictably.
19. Explain Route 53.
Route 53 is a scalable DNS web service for domain registration, routing traffic to resources via health checks and routing policies like latency-based.
20. What is Amazon DynamoDB?
DynamoDB is a NoSQL database, fully managed, serverless with single-digit millisecond latency. It supports on-demand capacity and global tables for multi-region replication.
Advanced AWS Interview Questions (3-6 Years Experience)
21. How would you design high availability for a web application on AWS?
Deploy EC2 instances in an Auto Scaling Group across multiple AZs behind an ALB. Use RDS Multi-AZ, EFS for shared storage, and CloudFront for CDN.
22. Scenario: Your EC2 CPU hits 80%. How do you scale?
Create an Auto Scaling Group with a scaling policy triggering on CloudWatch alarm for CPU >80%. It adds instances; use target tracking for desired capacity.
23. Differences between batch and real-time data processing in AWS?
Batch processes large static data periodically (e.g., Glue ETL). Real-time handles streams continuously with low latency (e.g., Kinesis, Lambda).
24. How to set up a data lake on AWS?
Use S3 for storage, Glue for ETL and catalog, Athena for querying, Lake Formation for governance, and QuickSight for visualization.
25. Explain VPC Peering and its use cases.
VPC Peering connects two VPCs privately for resource sharing. Use cases: cross-account access or multi-VPC architectures without internet gateways.
26. Scenario: Monitor RDS IOPS and alert operations team.
Use CloudWatch metrics for Read/Write IOPS, create alarms, and send SNS notifications to the team’s email or Lambda for custom actions.
27. How to optimize costs in AWS?
Use Reserved/Spot Instances, Auto Scaling, S3 lifecycle policies, CloudFront caching, and Trusted Advisor for recommendations.
28. What is AWS CodePipeline?
CodePipeline automates CI/CD pipelines, integrating CodeCommit, CodeBuild, CodeDeploy for build, test, and deployment stages.
29. Scenario: Ensure ACID compliance for app data on EC2 with EBS.
Mount Amazon EFS on instances across AZs behind an ALB with Auto Scaling. EFS provides shared, durable file storage meeting ACID properties.
30. How to implement disaster recovery on AWS?
Use Multi-Region setup with CloudFormation for replication, RDS read replicas cross-region, S3 cross-region replication, and regular backup testing.
Master these AWS interview questions to confidently tackle roles at product companies like Salesforce or startups like Swiggy. Practice hands-on in the AWS console for best results.
