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:
high availability AWS, fault-tolerant AWS architecture, AWS scenario based question high availability
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:
AWS database migration interview,
minimal downtime AWS, DMS migration scenario
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:
AWS EC2 scaling interview, auto scaling scenario question, handle traffic spike AWS
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:
secure S3 AWS, S3 encryption scenario AWS, AWS data security interview
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:
AWS GDPR compliance, AWS data privacy interview, cloud compliance scenario AWS
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:
AWS serverless scenario, Lambda interview question AWS, serverless architecture AWS
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:
AWS EC2 troubleshooting, EC2 not starting scenario, AWS support interview question
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:
VPC isolation scenario AWS, AWS security group interview, isolate EC2 from internet
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:
AWS automation interview, cloudformation scenario AWS, devops aws scenario question
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:
AWS Lambda monitoring, Lambda debugging scenario, memory issue AWS Lambda
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