Top 20 AWS Questions for Experienced Developers

1. What is Amazon EC2?

Business Use Case: “Where would you host the main Java application for our claims processing system?”

Answer: Amazon EC2 (Elastic Compute Cloud) provides virtual servers, called instances, in the cloud. It’s the backbone of AWS, allowing you to run applications. For the claims processing system, I would deploy our Spring Boot application on a set of EC2 instances.

2. What is Amazon S3?

Business Use Case: “Where would you store generated EOB (Explanation of Benefits) documents, claim attachments, and daily data backups?”

Answer: Amazon S3 (Simple Storage Service) is a highly scalable and durable object storage service. It’s perfect for storing unstructured data like PDF documents, images, and backups. I would use S3 to store all generated EOBs and any supporting documents attached to a claim.

3. What is AWS Lambda?

Business Use Case: “We need to automatically process a claim attachment as soon as it’s uploaded. How can we do this without a dedicated server running 24/7?”

Answer: AWS Lambda is a serverless compute service. It lets you run code in response to events without managing servers. I would configure a Lambda function to be triggered whenever a new file is uploaded to a specific S3 bucket. The function would then process the attachment, for example, by running OCR to extract text.

4. What is Amazon RDS?

Business Use Case: “Where would you store structured data like member profiles, policy information, and claim details?”

Answer: Amazon RDS (Relational Database Service) is a managed service for relational databases like PostgreSQL, MySQL, and Oracle. It automates administrative tasks like backups and patching. I would use RDS with PostgreSQL to store the core transactional data for our insurance platform.

5. What is Amazon DynamoDB?

Business Use Case: “We need to store a high volume of audit logs for every action taken on a claim, and we need to retrieve them with very low latency. Would a relational database be a good fit?”

Answer: For this use case, a NoSQL database like Amazon DynamoDB is a better fit. It’s designed for high-volume, low-latency key-value lookups. Storing audit logs in DynamoDB would be much faster and more scalable than using a relational database.

6. What is a VPC?

Business Use Case: “How do you ensure that our entire insurance platform, including its databases and internal services, is isolated from the public internet for security?”

Answer: A VPC (Virtual Private Cloud) allows you to create a logically isolated section of the AWS cloud where you can launch resources in a virtual network that you define. I would place all our application servers and databases in private subnets within a VPC, with no direct access from the internet.

7. What are Security Groups?

Business Use Case: “How do you allow the ClaimService to connect to the MemberDatabase on the PostgreSQL port, but block all other traffic?”

Answer: Security Groups act as a virtual firewall for EC2 instances. They control inbound and outbound traffic. I would create a security group for the database that only allows inbound traffic on port 5432 from the security group attached to the ClaimService instances.

8. What is an Elastic Load Balancer (ELB)?

Business Use Case: “Our claim submission API will be used by thousands of providers. How do we distribute the traffic evenly across multiple instances of our application?”

Answer: An ELB (Elastic Load Balancer) automatically distributes incoming application traffic across multiple targets, such as EC2 instances. I would place an Application Load Balancer (ALB) in front of our ClaimService instances to ensure high availability and scalability.

9. What is Auto Scaling?

Business Use Case: “During open enrollment season, traffic to our member portal increases by 5x. How can we handle this load without manually adding servers?”

Answer: An Auto Scaling Group automatically adjusts the number of EC2 instances to meet demand. I would configure it to monitor the CPU utilization of our instances. If the average CPU goes above 70%, it would automatically launch new instances. When the traffic decreases, it would terminate the extra instances to save costs.

10. What is AWS IAM?

Business Use Case: “How do you give our ClaimService permission to read and write to an S3 bucket, but prevent it from deleting anything?”

Answer: AWS IAM (Identity and Access Management) is used to manage access to AWS services securely. I would create an IAM Role with a policy that grants specific permissions (e.g., s3:GetObject, s3:PutObject) to the S3 bucket. I would then assign this role to the EC2 instances running the ClaimService. This is much more secure than hard-coding API keys.

11. What is Amazon SQS?

Business Use Case: “When a claim is submitted, we need to put it into a queue for a separate batch process to adjudicate later. How can we ensure no claims are lost if the batch process is temporarily down?”

Answer: Amazon SQS (Simple Queue Service) is a fully managed message queuing service. The API service would send a message containing the claim details to an SQS queue. This decouples the services. The batch process can then pull messages from the queue at its own pace. If the batch process is down, the messages will be safely stored in the queue until it comes back online.

12. What is Amazon SNS?

Business Use Case: “When a claim is finalized, we need to notify multiple downstream systems: the payment service, the EOB generation service, and an audit service. How can we do this efficiently?”

Answer: Amazon SNS (Simple Notification Service) is a publish/subscribe messaging service. The ClaimService would publish a single ClaimFinalized message to an SNS topic. All interested services can subscribe to this topic and will receive a copy of the message. This is a great way to fan out notifications to multiple systems.

13. What is the difference between SQS and SNS?

Answer: The key difference is the delivery model. SNS uses a pub/sub model where a message is pushed to many subscribers. SQS uses a polling model where a message is sent to a queue, and a single consumer pulls and processes it. You often use them together: an SNS topic can have an SQS queue as one of its subscribers for durable, asynchronous processing.

14. What is AWS CloudWatch?

Business Use Case: “How do you monitor our production services and get an alert if the claim adjudication service’s CPU usage is too high or if it starts logging a lot of errors?”

Answer: AWS CloudWatch is a monitoring service. It collects logs, metrics, and events. I would use it to:

  • Collect Metrics: Track CPU Utilization, memory, and other metrics from our EC2 instances.
  • Set Alarms: Create an alarm that sends a notification (e.g., via SNS) if CPU usage stays above 80% for 5 minutes.
  • Centralize Logs: Ship all application logs to CloudWatch Logs for centralized searching and analysis.

15. What is an API Gateway?

Business Use Case: “Our frontend portal needs to call multiple microservices (Member, Claim, Provider). How can we provide a single, secure entry point for all these calls?”

Answer: Amazon API Gateway is a managed service for creating and managing APIs. It acts as a “front door” for our backend services. It can handle request routing, authentication and authorization, rate limiting, and caching, which simplifies the logic in our downstream microservices.

16. What is AWS CloudFormation?

Business Use Case: “We need to set up a new, identical environment for a new client. How can we do this quickly and without manual errors?”

Answer: AWS CloudFormation is an Infrastructure as Code (IaC) service. I would define our entire infrastructure—VPC, EC2 instances, databases, load balancers—in a YAML or JSON template. We can then use this template to automatically and repeatably provision the entire stack of resources, ensuring consistency and reducing manual effort.

17. What is AWS Elastic Beanstalk?

Business Use Case: “A small team needs to quickly deploy a simple member-facing web application without having to worry about configuring servers, load balancers, or auto-scaling.”

Answer: AWS Elastic Beanstalk is a Platform as a Service (PaaS) that automates the deployment and management of applications. The team can just upload their code (e.g., a WAR file), and Elastic Beanstalk automatically handles the provisioning of servers, load balancing, and scaling. It’s great for simple applications where you don’t need fine-grained control over the infrastructure.

18. What is AWS ECS?

Business Use Case: “We are moving our microservices to Docker containers. How can we run and manage these containers at scale on AWS?”

Answer: AWS ECS (Elastic Container Service) is a container orchestration service. It allows us to define our application as a set of services and tasks, and ECS takes care of placing the containers on a cluster of EC2 instances, managing their lifecycle, and integrating with load balancers.

19. What is AWS Secrets Manager?

Business Use Case: “How do we securely store and manage database passwords and third-party API keys without hard-coding them in our application’s configuration files?”

Answer: AWS Secrets Manager is a service for securely storing and managing secrets. We can store our database credentials in Secrets Manager and use IAM roles to give our application permission to retrieve them at runtime. It also supports automatic rotation of secrets, which is a key security best practice.

20. What is AWS CloudFront?

Business Use Case: “Our member portal has static assets like images, CSS, and JavaScript files. How can we ensure these files load quickly for users across the country?”

Answer: AWS CloudFront is a Content Delivery Network (CDN). It caches copies of your static content in “edge locations” around the world, closer to your users. When a user requests a file, it’s served from the nearest edge location instead of your main server, which significantly reduces latency and improves load times.

21. Explain the difference between RDS and DynamoDB in more detail.

Business Use Case: “In our insurance platform, we need to store member policy details, which have complex, structured relationships. We also need to store user session data for our web portal, which requires very fast reads and writes. Which database would you choose for each, and why?”

Answer: This scenario perfectly highlights why you’d choose one over the other. They are both managed databases but are designed for fundamentally different problems.

Feature Amazon RDS (Relational) Amazon DynamoDB (NoSQL)
Data Model Tables with rows and columns (like a spreadsheet). Key-value pairs and documents (like a JSON object).
Schema Fixed and predefined. You must define your table structure before you insert data. Flexible. Each item can have a different structure.
Scalability Scales vertically (by increasing the server’s CPU/RAM). Can be complex to scale horizontally. Scales horizontally (by adding more servers/partitions). Built for massive scale.
Querying Powerful and flexible using SQL. Excellent for complex queries, joins, and aggregations. Optimized for very fast reads/writes based on a primary key. Complex queries are less efficient.

  • For Member Policy Data, I would choose Amazon RDS (e.g., PostgreSQL).

    • The data is highly structured with clear relationships (members, policies, dependents).
    • We need the power of SQL to run complex reports, like “find all members in a specific group who have a dental plan.”
    • Transactional integrity (ACID compliance) is critical to ensure data consistency.

  • For User Session Data, I would choose Amazon DynamoDB.

    • The data structure is simple (e.g., sessionId as the key and user data as the value).
    • The primary requirement is extremely fast reads and writes to provide a snappy user experience. We are always fetching the data by a single key (sessionId).
    • It can handle massive traffic spikes without performance degradation.