Prepare for your AWS interview with these 30 essential questions and answers. Covering basic, intermediate, and advanced topics, this guide helps freshers, candidates with 1-3 years of experience, and professionals with 3-6 years of experience master AWS concepts, practical implementations, and real-world scenarios.
Basic AWS Interview Questions
1. What is AWS and what are its key features?
AWS is a comprehensive cloud computing platform providing services like compute, storage, and networking. Key features include scalability, high availability through Regions and Availability Zones, pay-as-you-go pricing, and global infrastructure.[1][7]
2. Explain the difference between AWS Regions and Availability Zones.
A Region is a geographic area with multiple isolated Availability Zones (AZs). AZs are separate data centers within a Region for fault tolerance. For example, US East (N. Virginia) Region has AZs like us-east-1a.[4][7]
3. What is Amazon EC2?
Amazon EC2 provides resizable virtual servers (instances) for running applications. You launch instances from Amazon Machine Images (AMIs) and scale them as needed.[3][6]
4. What is Amazon S3?
Amazon S3 is object storage for durable, scalable data storage. It offers storage classes like Standard, Intelligent-Tiering, and Glacier for different access patterns.[1][5]
5. What is AWS IAM?
AWS Identity and Access Management (IAM) manages user permissions and access to AWS services via policies, roles, and users.[2][3]
6. Differentiate between stopping and terminating an EC2 instance.
Stopping an EC2 instance releases compute capacity but retains the EBS-backed root volume. Terminating deletes the instance and its root volume data.[3]
7. What is Amazon CloudWatch?
CloudWatch monitors AWS resources and applications, collecting metrics, logs, and setting alarms like high CPU usage alerts on EC2.[4]
8. Name the difference between AWS Config and CloudTrail.
AWS Config tracks resource configurations and changes over time. CloudTrail logs API calls and user actions across the account.[4]
9. What are Security Groups in AWS?
Security Groups act as virtual firewalls for EC2 instances, controlling inbound and outbound traffic. By default, inbound is denied, outbound is allowed.[3][5]
10. What is Auto Scaling?
Auto Scaling automatically adjusts EC2 capacity based on demand to maintain performance and cost efficiency.[5]
Intermediate AWS Interview Questions
11. How do you enable high availability for a web application on AWS?
Deploy EC2 instances in an Auto Scaling group across multiple AZs behind an Elastic Load Balancer (ELB). Use RDS Multi-AZ for the database.[2][3]
12. What is Amazon VPC?
Virtual Private Cloud (VPC) provides an isolated network environment. It includes subnets, route tables, internet gateways, and security controls.[2][6]
13. Explain VPC Peering and its use cases.
VPC Peering connects two VPCs for private communication. Use cases include sharing resources between VPCs in development at Zoho or production environments.[2]
14. What is Amazon RDS?
RDS is a managed relational database service supporting engines like MySQL, PostgreSQL. It handles backups, patching, and Multi-AZ deployments.[2][6]
15. Differentiate between horizontal and vertical scaling.
Vertical scaling increases instance size (CPU/RAM). Horizontal scaling adds more instances behind a load balancer for better fault tolerance.[4]
16. What is AWS Lambda?
AWS Lambda runs code without provisioning servers, executing functions on triggers like S3 uploads. Pay only for execution time.[5]
17. How does Amazon CloudFront work?
CloudFront is a CDN caching content at edge locations to reduce latency. Use it for static web assets in applications at Flipkart.[2][4]
18. What are NACLs in VPC?
Network ACLs are stateless subnet-level firewalls controlling inbound/outbound traffic, complementing stateful Security Groups.[5]
19. Explain Cross-Region Replication in S3.
Cross-Region Replication asynchronously copies objects between S3 buckets in different Regions for disaster recovery.[5]
20. What is Elastic Load Balancing (ELB)?
ELB distributes incoming traffic across EC2 instances in multiple AZs for high availability and fault tolerance.[1][2]
Advanced AWS Interview Questions
21. How would you design a fault-tolerant system on AWS?
Implement redundancy across AZs, use Auto Scaling and ELB, enable automated monitoring with CloudWatch, and set up regular backups.[1]
22. Scenario: Your application at Paytm experiences high traffic spikes. How do you handle it?
Configure Auto Scaling groups with CloudWatch metrics to scale EC2 instances. Use ELB to distribute traffic and S3 for static content.[1][2]
23. What is AWS KMS vs CloudHSM?
KMS is a managed key service for encryption. CloudHSM provides dedicated hardware modules for full key control in compliant environments like at Salesforce.[4]
24. How do you set up disaster recovery for a critical application?
Use S3 Cross-Region Replication, store AMIs in another Region, set up a secondary VPC, and use DMS for database replication. Test regularly.[2]
25. Explain cost optimization strategies in AWS.
Use Reserved/Spot Instances, Auto Scaling, S3 lifecycle policies, and caching with ElastiCache and CloudFront.[1]
26. Scenario: Build a data lake architecture on AWS.
Store raw data in S3, use AWS Glue for ETL, Athena for querying, IAM/Lake Formation for security, and QuickSight for visualization.[1]
27. What is AWS Direct Connect vs VPN?
Direct Connect offers dedicated low-latency connections. VPN uses public internet with potential variable latency, suitable for quick setups at Swiggy.[4]
28. Differentiate CodePipeline and CodeDeploy.
CodePipeline orchestrates CI/CD pipelines. CodeDeploy deploys applications to EC2, Lambda, or on-premises servers.[4]
29. How do you ensure security in a VPC?
Use Security Groups for instance-level control, NACLs for subnet-level, IAM roles, VPC Flow Logs, and encryption with KMS.[5]
30. Scenario: At Atlassian, ensure microservices resilience. What AWS features?
Design for fault isolation across AZs, use AWS Well-Architected Framework for reliability, implement distributed tracing with X-Ray, and monitoring.[1]
