Prepare for your AWS interview with this comprehensive guide featuring 30 essential questions and answers. Covering basic, intermediate, and advanced topics, these questions target freshers, candidates with 1-3 years of experience, and professionals with 3-6 years in AWS. Each answer provides clear, practical insights into AWS services like EC2, S3, VPC, Lambda, and more.
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 offering scalable infrastructure services. Key features include high availability through Regions and Availability Zones, pay-as-you-go pricing, security with IAM, and services like compute (EC2), storage (S3), and databases (RDS).[8]
2. Explain Regions and Availability Zones in AWS.
AWS Regions are geographic locations with multiple isolated Availability Zones (AZs). Each AZ is a data center cluster with independent power and networking. Deploying across AZs ensures high availability and fault tolerance.[8]
3. What is Amazon EC2?
Amazon EC2 (Elastic Compute Cloud) provides resizable virtual servers in the cloud. You launch instances for web hosting, applications, or computing, choosing instance types for CPU, memory, and storage needs.[7]
4. What is Amazon S3?
Amazon S3 (Simple Storage Service) is object storage for scalable data storage. It offers 99.999999999% durability, supports unlimited storage, and provides access via HTTP with storage classes like Standard and Glacier.[2]
5. What is AWS IAM?
AWS Identity and Access Management (IAM) controls user permissions and access to AWS services. Create users, groups, roles, and policies to manage security, following least privilege principles.[2]
6. 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 and outbound is allowed. Rules specify protocols like HTTP (port 80) or SSH (port 22).[5]
7. What is Amazon CloudWatch?
Amazon CloudWatch monitors AWS resources and applications. It collects metrics, logs, and sets alarms for CPU usage or errors, enabling automated responses.[6]
8. What is AWS Lambda?
AWS Lambda is a serverless compute service running code in response to events without provisioning servers. It scales automatically and charges per execution, ideal for microservices.[2]
9. Name different S3 storage classes.
S3 storage classes include Standard (frequent access), Intelligent-Tiering (automatic optimization), Standard-IA (infrequent access), One Zone-IA, Glacier (archival), and Glacier Deep Archive (long-term storage).[2]
10. What is Auto Scaling in AWS?
AWS Auto Scaling automatically adjusts EC2 capacity based on demand. Auto Scaling Groups maintain desired instance counts using CloudWatch metrics like CPU utilization.[2]
Intermediate AWS Interview Questions (1-3 Years Experience)
11. Differentiate between stopping and terminating an EC2 instance.
Stopping an EC2 instance releases compute resources but retains the EBS root volume and data. Terminating deletes the instance and optionally the root volume, preventing reuse.[1]
12. How does EBS ensure data durability?
EBS volumes replicate data within an Availability Zone for 99.999% durability. For higher protection (11 9s), create snapshots stored in S3.[3]
13. What is Amazon RDS?
Amazon RDS is a managed relational database service supporting engines like MySQL, PostgreSQL, and SQL Server. It handles backups, patching, and Multi-AZ deployments for high availability.[4]
14. Explain VPC and its components.
A VPC (Virtual Private Cloud) is an isolated network in AWS. Components include subnets (public/private), route tables, internet gateways, NAT gateways, and security groups for traffic control.[4]
15. How do you configure VPC peering?
VPC peering connects two VPCs for private communication. Create a peering request in one VPC, accept in the other, then update route tables and security groups to allow traffic.[4]
16. What is Elastic Load Balancing (ELB)?
ELB distributes incoming traffic across EC2 instances for high availability. Types include Application Load Balancer (ALB) for HTTP/HTTPS, Network Load Balancer (NLB) for TCP, and Gateway Load Balancer.[2]
17. Differentiate between S3 buckets and EBS volumes.
S3 buckets store objects globally with high durability, suitable for unstructured data. EBS volumes are block storage for EC2 instances, attached like virtual hard drives within a single AZ.[3]
18. What is Amazon CloudFront?
Amazon CloudFront is a CDN caching content at edge locations worldwide. It reduces latency for static assets like images from S3 by serving from the nearest edge.[4]
19. Explain Lambda versions and aliases.
A Lambda version is an immutable snapshot of code and configuration. An alias points to a version, enabling traffic shifting between versions for dev/prod environments.[3]
20. What is Amazon Route 53?
Route 53 is a scalable DNS service with routing policies like latency-based, geolocation, and health checks for failover. It integrates with ELB and S3.[3]
Advanced AWS Interview Questions (3-6 Years Experience)
21. Design a highly available web application architecture on AWS.
Deploy EC2 instances in Auto Scaling Groups across multiple AZs behind an ALB. Use RDS Multi-AZ for database, S3 for static assets with CloudFront CDN, and Route 53 for DNS failover.[2]
22. Explain the AWS Well-Architected Framework.
The framework has six pillars: Operational Excellence (automation), Security (IAM, encryption), Reliability (fault tolerance), Performance Efficiency (right-sizing), Cost Optimization (reserved instances), and Sustainability.[2]
23. How to design a CI/CD pipeline for containerized apps?
Use CodePipeline with CodeCommit source, CodeBuild for building Docker images to ECR, and CodeDeploy to ECS/EKS. Implement blue-green deployments for zero-downtime.[2]
24. Troubleshoot 502 errors in a web app during peak traffic at Paytm.
Check ALB logs for patterns, verify target health, review app logs and timeouts, inspect security groups, and monitor CloudWatch metrics for capacity issues.[2]
25. Design a multi-region active-active architecture.
Use Route 53 latency routing to nearest region with API Gateway, Lambda/ECS. Replicate data via DynamoDB Global Tables and S3 cross-region replication with health checks.[3]
26. How to reduce costs in AWS?
Use Reserved/Spot Instances, Auto Scaling, S3 lifecycle policies, Intelligent-Tiering, and ElastiCache/CloudFront for caching to optimize compute and data transfer costs.[1]
27. Minimize downtime in Elastic Beanstalk blue/green deployment.
Deploy new version to a separate environment, test, then swap CNAMEs for traffic redirection. This enables zero-downtime with easy rollback.[3]
28. Reduce latency for global users with DynamoDB at Zoho.
Implement DynamoDB Global Tables for multi-region replication and Route 53 latency routing to direct users to the nearest read region.[3]
29. Design a data lake architecture on AWS.
Store raw data in S3, use AWS Glue for ETL, IAM/Lake Formation for security, Athena for querying, Redshift Spectrum for analytics, and QuickSight for visualization.[1]
30. Ensure system resilience in microservices at Salesforce.
Implement redundancy, load balancing, automated monitoring with CloudWatch, fault isolation, backups, and use the Well-Architected Framework for evaluation.[1]
