10 AWS Interview Questions and Answers

Memorizing definitions is not enough to prepare for a 2026 cloud-focused role -- you will need to be able to have the vocabulary, architecture, cost optimization, and hands-on way feeling comfortable. The bar for technical competence has never been higher, as companies move towards serverless-first and AI-integrated architectures.

In this AWS Interview Questions blog, I have also mentioned some of the top questions asked in an AWS interview. We're not going to bore you with the "Introduction" definition included in most listicles; we will let you learn more about it throughout this examination, instead teaching you real-life examples and architectural insights at our disposal, ready to make us shine.

Q 1. What is the difference between Scalability and Elasticity in AWS?

This is one of the basic AWS Interview Questions and Answers. Even though the terms are used interchangeably, they imply different architectural purposes.

Scale – Ability of the system to be increased in size by adding resources. In AWS, you might classify that as Vertical (changing instance size, i.e., from t3. micro to m5. large), or Horizontal (multiple of the same size).

Elasticity: A system’s ability to automatically grow and shrink in response to real-time demand. You can handle this, which is mainly managed by AWS Auto Scaling.

Real-Life Use Case: Think of an online shopping platform on Black Friday. Scaling makes the infrastructure capable of handling up to 1 million active users. This elasticity is the reason why, at 3:00 AM, when we have less traffic, those servers that we don't need are all shut down to save money.

Q 2. How do you secure a multi-tier application on a VPC?

Every blog in this series (AWS Interview Questions and Answers) will appear at the top of the search results. A strong design is based on Defence in Depth.

Public Subnet: Contains the Application Load Balancer (ALB) and Bastion Host.

Private Subnet: Contains the EC2 application servers (no inbound internet access).

Database Subnet: A single isolated private subnet for RDS or DynamoDB.

Security Groups vs. NACLs: Use Security Groups (stateful) for protection at the instance level and Network Access Control Lists (stateless) for subnet-level protection.

Q 3. What the heck is AWS Lambda, and how does it manage "Cold Starts"?

Lambda: One of the Top 10 AWS Interview Questions. Lambda is the move toward serverless. Cold Start is what we call it when a function is invoked once it’s been idle; there will be latency while AWS spins up a new container.

Programming Example (Node. js optimization): Minimize cold starts by keeping the deployment package small and moving database connections outside the handler function.

// Database connection outside of the handler's scope

// this is warm across invocations.

const dbConnection = connectToDatabase();

exports. handler = async (event) => {

// Business logic works with the warm connection.

const data = await dbConnection. query('SELECT * FROM users');

return {

statusCode: 200,

body: JSON. stringify(data),

};

};

Q4. What is the AWS Shared Responsibility Model?

It’s a “need-to-know” for any AWS Q&A list.

Security OF the Cloud-SAAS-AWS is responsible for this: Protecting the global infrastructure that hosts all of the services you deploy to potential customers (hardware, software, networking, and facilities).

The Customer is in charge of “Security IN the Cloud”: Encryption, Data Security Management (IP, IAM), and Firewall Rules.

Q 5. You can do it with Blue/Green Deployments on Amazon Web Services.

Blue/Green deployment is a technique to attain zero-downtime deployments by running two identical production environments.

Blue: The current live version.

Green: The new version.

Switch: Route traffic from Blue to Green with Route 53 weighted routing or an ALB. If you find a bug, you can quickly roll back by moving traffic back to Blue.

Q 6. What are the different EC2 Purchase Options?

AWS architects are obsessed with costs.

On-Demand: Pay by the second. Best for short-term, unpredictable workloads.

Reserved Instances (RI) / Savings Plans: Up to 72% off on a commitment for up to 1-3 years.

Spot Instances: On-Demand capacity at up to 90% off. Best for jobs that can tolerate failure (batch processing).

Dedicated Hosts – Physically isolated servers for compliance/licensing requirements.

Q 7. How could code infrastructure be created with AWS CloudFormation?

CloudFormation Is An IaC tool. You can specify your whole stack in a JSON or YAML template.

Code Example (YAML CloudFormation Template): The following sample provisions an S3 bucket with versioning enabled.

Resources:

MyS3Bucket:

Type: 'AWS::S3::Bucket'

Properties:

BucketName: my-unique-interview-bucket-2026

VersioningConfiguration:

Status: Enabled

Q 8. What are the Key differences between GSI and LSI in Dynamo DB?

This is one of the popular “Deep Dive” questions that you may expect in a typical AWS interview Questions and Answers.

LSI: We can only have LSIs that we define when creating the table. It has the same Partition Key as the Table but a different Sort Key.

GSI: Can be added or removed at any time. It may have an entirely different Partition Key and Sort Key than the base table.

Q 9. How is High availability offered by Route 53?

Route 53 isn’t just a DNS; it’s also a traffic management service. It monitors your endpoints using Health Checks. So whether an instance fails or a region goes dark, Route 53 can automatically direct users to a resource that is still up and running using either:

Failover Routing: Primary/Secondary setup.

Geolocation Routing: Routes users in accordance with their geographic location.

Latency Routing: Routes users to the region with the lowest network latency.

Q 10. You have to move a 2TB on-premises PostgreSQL database with less than 5 minutes of downtime to AWS RDS. What is your strategy?

Answer:  Use AWS Database Migration Service (DMS) and Change Data Capture (CDC).

Full Load – Initial bulk copy of data from on-prem to RDS through DMS_pub. Use DMS 70.0_average_pub 12 DMS can be used for initial bulk load and/or one time migration jobs. The site remains online and functioning during that time.

Changing data capture (CDC): DMS simply records every insert, update or delete that occurs on the source whilst you are generating your new RDS instance, providing you a near up to date copy.

Cutover: When the `Time Drift` drifts between source and target is close to zero seconds, you pull the plug on your application, let a few transactions catch up (or cut over at some known transaction boundary), change what your applications think of as where database.connection.string goes to eg. RDS's endpoint and restart it. It makes downtime just the time to update the config and restart the app.

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