Prepare for your AWS job interview with these 30 essential AWS interview questions covering EC2, S3, VPC, Lambda, and more. Organized from basic to advanced levels, these questions target freshers, 1-3 years, and 3-6 years experienced candidates. Each answer provides clear, practical insights grounded in AWS best practices.
Basic AWS Interview Questions (Freshers)
1. What are Regions and Availability Zones in AWS?
Regions are geographic areas like US East (N. Virginia), each containing multiple isolated Availability Zones. Availability Zones are separate data centers within a region for high availability and fault tolerance.[5]
2. What is Amazon EC2?
Amazon EC2 provides resizable compute capacity in the cloud. It allows launching virtual servers (instances) to run applications, with options for different instance types based on CPU, memory, and storage needs.[4]
3. Explain Amazon S3 and its key features.
Amazon S3 is object storage for scalable data storage. Key features include 99.999999999% durability, versioning, lifecycle policies, and storage classes like Standard and Glacier for cost optimization.[1]
4. What is AWS Lambda?
AWS Lambda is a serverless compute service that runs code in response to events without provisioning servers. You pay only for compute time consumed.[6]
5. Differentiate between horizontal and vertical scaling in AWS.
Horizontal scaling adds more instances (e.g., via Auto Scaling Groups). Vertical scaling increases resources on a single instance (e.g., upgrading EC2 type).[5]
6. What is Amazon CloudWatch?
Amazon CloudWatch monitors AWS resources and applications. It collects metrics, logs, and sets alarms, such as for high CPU on EC2 instances.[5]
7. What are Security Groups in AWS?
Security Groups act as virtual firewalls for EC2 instances, controlling inbound and outbound traffic. By default, all inbound is denied, outbound allowed.[4]
8. What is Amazon RDS?
Amazon RDS is a managed relational database service supporting engines like MySQL and PostgreSQL. It handles backups, patching, and scaling.[3]
9. Explain Cross-Region Replication in S3.
Cross-Region Replication asynchronously copies objects from one S3 bucket to another in a different region for disaster recovery and low-latency access.[6]
10. What is an AMI in AWS?
An AMI (Amazon Machine Image) is a template for launching EC2 instances, containing OS, software, and configurations. Snapshots back AMIs for recovery.[2]
Intermediate AWS Interview Questions (1-3 Years Experience)
11. How do you achieve high availability for a web application on AWS?
Use EC2 Auto Scaling Groups behind Elastic Load Balancing across multiple Availability Zones, with RDS Multi-AZ for database failover.[3]
12. What is the difference between EBS and Instance Store?
EBS volumes persist independently of instance lifecycle and can be attached to other instances. Instance Store is ephemeral, tied to instance lifetime for temporary data.[2]
13. Explain VPC and its components.
A VPC is a virtual private cloud for isolated networking. Components include subnets, route tables, internet gateways, and NAT gateways for public/private access.[3]
14. How does AWS ensure data durability in EBS volumes?
EBS volumes replicate automatically within an Availability Zone for 99.999% durability. Use snapshots in S3 for 11 9’s durability.[2]
15. What is the difference between a Lambda version and alias?
A version is an immutable snapshot of Lambda code/config. An alias points to a version, enabling traffic routing for environments like dev/prod.[2]
16. How do you configure Auto Scaling in AWS?
Create a Launch Template, define scaling policies based on CloudWatch metrics like CPU utilization, and attach to an Auto Scaling Group across AZs.[1]
17. What is Amazon CloudFront?
CloudFront is a CDN that caches content at edge locations worldwide, reducing latency for static/dynamic web content from origins like S3/EC2.[3]
18. Explain IAM roles versus IAM users.
IAM users have long-term credentials for humans/services. IAM roles provide temporary credentials for apps/services like EC2 without sharing keys.[1]
19. How do you set up VPC Peering?
Create a peering connection request from one VPC owner, accept from the peer VPC, then update route tables to allow traffic between CIDR blocks.[3]
20. What are S3 Lifecycle Policies?
S3 Lifecycle Policies automate transitions (e.g., Standard to Glacier) and expirations to optimize storage costs for infrequently accessed data.[1]
Advanced AWS Interview Questions (3-6 Years Experience)
21. How would you design a multi-region active-active architecture at Zoho?
Use Route 53 latency routing to nearest region, deploy API Gateway/Lambda/ECS per region, DynamoDB Global Tables for data, and S3 Cross-Region Replication with health checks.[2]
22. Minimize downtime in Elastic Beanstalk blue/green deployments.
Deploy new version to a separate environment, test, then swap CNAMEs for zero-downtime. Rollback by swapping back.[2]
23. Reduce latency for global users with DynamoDB at Paytm.
Implement DynamoDB Global Tables for multi-region replication, Route 53 latency routing, handling eventual consistency in app logic.[2]
24. Design a cost-optimized scalable system at Salesforce.
Use Reserved/Spot Instances, Auto Scaling, S3 Intelligent-Tiering, CloudFront/ElastiCache for caching to cut compute/storage/transfer costs.[1]
25. Build a data lake architecture on AWS for Swiggy.
Store raw data in S3, use AWS Glue for ETL, IAM/Lake Formation for security, Athena for queries, Redshift Spectrum/QuickSight for analytics.[1]
26. Ensure fault tolerance in microservices at Atlassian.
Implement redundancy, load balancing, automated monitoring, fault isolation, backups, disaster recovery, and graceful degradation.[1]
27. Difference between AWS Direct Connect and VPN.
Direct Connect offers dedicated low-latency bandwidth. VPN uses public internet, easier setup but variable latency.[5]
28. Design disaster recovery for critical data at Adobe.
Enable S3 cross-region replication, AMI backups, secondary region VPC with CloudFormation, DMS for DB replication, automated backups, regular DR testing.[3]
29. Use AWS Well-Architected Framework for evaluation.
Review pillars: operational excellence, security, reliability, performance efficiency, cost optimization using the AWS Well-Architected Tool.[1]
30. Route 53 routing policies for Flipkart traffic.
Use latency-based for lowest latency, geolocation for region-specific, health checks for failover. Not for device type (handle in app).[2]
