AWS Interview Questions and Answers (2025)

 AWS Interview Questions and Answers (2025) – Beginner to Expert  Basic AWS Interview Questions and Answers

Q1: What is AWS?

Answer:
Amazon Web Services (AWS) is a cloud computing platform offered by Amazon. It provides on-demand computing resources, such as servers, storage, databases, networking, and more, via a pay-as-you-go model. AWS supports a wide range of cloud services including IaaS (Infrastructure as a Service), PaaS, and SaaS.

Queries: AWS basics, what is AWS, AWS definition, cloud computing

 

Q2: What are the main benefits of using AWS?

Answer:

·         Scalability: Automatically scale up or down based on demand.

·         Cost-Effectiveness: Pay only for what you use.

·         Flexibility: Supports multiple OS and programming languages.

·         Security: Complies with industry-standard compliance and security.

·         Global Reach: Data centers in multiple regions and availability zones.

Queries: AWS benefits, AWS scalability, AWS cost efficiency

 

Q3: What are EC2 instances in AWS?

Answer:
Amazon EC2 (Elastic Compute Cloud) provides resizable compute capacity in the cloud. It allows users to launch virtual servers (instances) and configure CPU, memory, storage, and networking capacity.

Queries: EC2 instance, AWS virtual server, AWS compute

 

 Intermediate AWS Interview Questions and Answers

Q4: What is the difference between S3 and EBS in AWS?

Answer:

·         Amazon S3 (Simple Storage Service): Object storage ideal for storing files, backups, and media.

·         Amazon EBS (Elastic Block Store): Block storage used for EC2 instances, similar to a hard disk.

Queries: AWS S3 vs EBS, AWS storage types, cloud storage comparison

 

Q5: What is IAM in AWS?

Answer:
AWS Identity and Access Management (IAM) enables secure access control to AWS services. It allows you to create and manage users, groups, and permissions via policies.

Queries: IAM AWS, AWS access management, AWS security

 

Q6: What is an AWS Availability Zone?

Answer:
An Availability Zone (AZ) is a physically isolated data center within an AWS region. Each region has multiple AZs for fault tolerance and high availability.

Queries: AWS regions and zones, AWS availability zone explained

 

Advanced AWS Interview Questions and Answers

Q7: How does Auto Scaling work in AWS?

Answer:
AWS Auto Scaling monitors your applications and automatically adjusts capacity to maintain performance and minimize cost. It can scale out or in based on CloudWatch metrics or scheduled actions.

Queries: AWS Auto Scaling, dynamic scaling, EC2 scaling

 

Q8: What is the difference between Elastic Load Balancer (ELB) and Application Load Balancer (ALB)?

Answer:

·         ELB: General term for load balancing across AWS services.

·         ALB: A layer 7 load balancer that routes HTTP/HTTPS traffic based on URL, host, or header.

Queries: ALB vs ELB, AWS load balancing, HTTP routing

 

Q9: What is AWS Lambda?

Answer:
AWS Lambda is a serverless compute service that runs your code in response to events. You don’t manage servers; you just upload your code and Lambda takes care of the rest.

Queries: AWS Lambda, serverless computing, event-driven architecture

 

Q10: What is Amazon VPC and why is it important?

Answer:
Amazon VPC (Virtual Private Cloud) lets you provision a logically isolated network in the AWS cloud. You control IP ranges, subnets, route tables, and gateways for network security and configuration.

Queries: AWS VPC, cloud networking, AWS private cloud

 

AWS Scenario-Based Interview Questions (Pro Level)

Q11: How would you design a highly available web application on AWS?

Answer:
Use a combination of:

·         Elastic Load Balancer (ELB) for distribution,

·         Auto Scaling for elasticity,

·         Multi-AZ deployment for fault tolerance,

·         RDS in Multi-AZ mode for database redundancy,

·         S3 for static content.

Queries: AWS architecture, high availability, AWS design patterns

 

Q12: How do you secure data at rest and in transit on AWS?

Answer:

·         At Rest: Use KMS for encryption with EBS, S3, and RDS.

·         In Transit: Use TLS/SSL for data transfer.

Queries: AWS data encryption, AWS security best practices

 

Final Tips for AWS Interviews:

·         Understand core services: EC2, S3, IAM, VPC, Lambda, RDS

·         Practice with real AWS console

·         Stay updated with AWS Well-Architected Framework

SEO-Optimized AWS Scenario-Based Interview Questions and Answers (2025)

 

Q1: How would you design a fault-tolerant and highly available architecture on AWS?

Answer:
To ensure high availability and fault tolerance:

·         Deploy applications across multiple Availability Zones (AZs).

·         Use an Elastic Load Balancer (ELB) to distribute traffic.

·         Use Auto Scaling Groups to manage EC2 capacity.

·         Store static files on Amazon S3.

·         Use Amazon RDS in Multi-AZ mode for database redundancy.

·         Leverage CloudFront CDN for content delivery.

Queries:
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Q2: You need to migrate an on-premise database to AWS with minimal downtime. What’s your approach?

Answer:

·         Use AWS Database Migration Service (DMS) for live replication.

·         Create a replica database in RDS or Aurora.

·         Perform a cutover during off-peak hours.

·         Ensure DNS changes propagate smoothly via Route 53.

Queries:
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Q3: A sudden traffic spike crashes your EC2 instance. How do you handle auto scaling in this scenario?

Answer:

·         Implement Auto Scaling policies based on CPU or memory metrics (CloudWatch alarms).

·         Use Elastic Load Balancing to distribute traffic evenly.

·         Set minimum and maximum instance counts to handle traffic bursts.

·         Store session state in Amazon ElastiCache or DynamoDB to ensure stateless architecture.

Queries:
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Q4: How would you secure sensitive data stored in Amazon S3?

Answer:

·         Enable S3 Bucket Policies and IAM access control.

·         Use server-side encryption (SSE-S3 or SSE-KMS).

·         Enable S3 Block Public Access to prevent unintended exposure.

·         Use AWS Macie to detect sensitive data.

Queries:
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Q5: Your application must comply with GDPR. How do you design it on AWS?

Answer:

·         Ensure data residency by selecting appropriate AWS regions.

·         Use AWS KMS for encryption and key control.

·         Enable audit logging with CloudTrail and Config.

·         Implement fine-grained access controls with IAM and resource policies.

·         Use AWS Shield & WAF for network protection.

Queries:
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Q6: A client wants a serverless solution with dynamic scaling. What AWS services would you use?

Answer:

·         Use AWS Lambda for compute.

·         Use API Gateway to expose REST APIs.

·         Store data in DynamoDB (serverless NoSQL).

·         Use Step Functions for orchestration if needed.

Queries:
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Q7: Your EC2 instance is not starting. What steps do you take to troubleshoot?

Answer:

·         Check CloudWatch logs and system status checks.

·         Inspect instance logs via EC2 console.

·         Confirm security group and NACL settings.

·         Try rebooting or stopping/starting the instance.

·         Check root EBS volume for corruption.

Queries:
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Q8: How do you isolate an EC2 instance in a public subnet from the internet?

Answer:

·         Remove the internet gateway (IGW) or modify route tables.

·         Revoke outbound access via security group or NACL.

·         Ensure no Elastic IP or public IP is attached.

·         Use VPC endpoints for private service access.

Queries:
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Q9: How would you automate the deployment of infrastructure on AWS?

Answer:

·         Use AWS CloudFormation or Terraform to manage IaC (Infrastructure as Code).

·         Use AWS CodePipeline and CodeBuild for CI/CD.

·         Define reusable templates with CloudFormation stacks.

Queries:
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Q10: You need to monitor and alert for a memory leak on a Lambda function. What’s your approach?

Answer:

·         Use CloudWatch Logs to monitor memory usage.

·         Set CloudWatch Alarms based on usage thresholds.

·         Use AWS X-Ray to trace performance bottlenecks.

·         Apply limits on Lambda memory configuration and monitor function duration.

Queries:
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