AWS Lambda Interview Questions in 2024

AWS Lambda Interview Questions

AWS Lambda has become a pivotal technology in the cloud computing landscape, enabling developers to run code in response to events without managing servers. Preparing for “AWS Lambda interview questions” is essential for professionals looking to showcase their expertise in serverless architectures. This guide will provide insights into typical questions and recommended responses to help candidates excel in their interviews.

What are AWS Lambda Interview Questions?

AWS Lambda interview questions assess a candidate’s technical knowledge and practical skills in using AWS Lambda, including their understanding of serverless architecture principles, event-driven solutions, and integration with other AWS services.

Most Common AWS Lambda Interview Questions


What is AWS Lambda, and how does it work?

Answer: “AWS Lambda is a serverless computing service provided by Amazon Web Services that allows developers to run code in response to events without provisioning or managing servers. Lambda automatically manages the compute resources by running the code in a high-availability computing infrastructure. It scales automatically by adjusting to the rate of incoming requests without requiring manual intervention.”

How do you secure a Lambda function?

Answer: “Securing a Lambda function involves several practices:

  • Assigning IAM roles to Lambda functions to ensure they have minimum necessary permissions.
  • Using AWS Lambda environment variables to handle sensitive information securely and encrypting them with AWS KMS.
  • Implementing VPC settings to isolate resources and control network access.
  • Using AWS WAF and Shield for protecting against web exploits and DDoS attacks.”

Can you explain the different ways to trigger a Lambda function?

Answer: “Lambda functions can be triggered in several ways, including:

  • Directly invoking via the AWS SDK.
  • Event sources such as S3 events, DynamoDB Streams, and Kinesis Streams.
  • Integrating with API Gateway for HTTP endpoints.
  • Scheduled events using Amazon CloudWatch Events.
  • Other AWS services like SNS and SQS for asynchronous processing.”

What are the limits of AWS Lambda?

Answer: “AWS Lambda has several limits, some of which are:

  • Memory allocation can range from 128 MB to 10,240 MB.
  • Execution timeout has a maximum limit of 15 minutes.
  • Deployment package size is 50 MB for zipped, direct upload and 250 MB for unzipped size including layers.
  • Concurrency limits, which can be set per function or shared across the account.”

How does Lambda handle state management?

Answer: “AWS Lambda is stateless; it does not preserve state across invocations. To handle state, you can use external services such as Amazon S3 for storage, Amazon DynamoDB for a NoSQL database solution, or integrate with other AWS services that can maintain state or session information.”

Describe a scenario where you optimized a Lambda function.

Answer: “In a recent project, we needed to reduce the execution time and cost of a Lambda function involved in image processing. By analyzing the function, I identified unnecessary external API calls and optimized the function by caching results in Amazon ElastiCache. This reduced the average execution time by 40% and lowered the cost due to decreased compute time.”

What are best practices for monitoring AWS Lambda?

Answer: “Best practices for monitoring AWS Lambda include:

  • Using Amazon CloudWatch for logs, metrics, and alarms to monitor function metrics like invocations, errors, and duration.
  • Implementing distributed tracing with AWS X-Ray to analyze and debug the performance of serverless applications.
  • Setting up custom metrics and logging for detailed application-specific insights.”

How do you manage dependencies in a Lambda function?

Answer: “To manage dependencies in Lambda, I package all necessary libraries along with my function code into a deployment package. For larger dependencies or to optimize function startup time, I use Lambda Layers, which allows sharing common components across multiple Lambda functions.”

How to Get Prepared for AWS Lambda Interview Questions

black and gray laptop computer

Deepen Your Technical Knowledge

Review core AWS services, especially those that integrate with Lambda, and understand the nuances of serverless architecture.

Hands-On Practice

Build sample projects using AWS Lambda to get practical experience with various triggers, configurations, and integrations.

Stay Updated

Keep up with the latest updates and features released by AWS for Lambda and other related services to ensure your knowledge is current.

Review Documentation and Case Studies

Study AWS documentation and case studies that showcase innovative uses of Lambda to understand its capabilities and limitations deeply.

Explore new advancements in serverless computing, focusing on architectural patterns, performance optimization, and cost management strategies.

  • Key Insight: Discuss how serverless models are evolving beyond just compute to encompass other aspects like containers and data processing.
  • Expert Tip: Offer insights into using architectural patterns like microservices and event-driven architectures with serverless technologies to enhance scalability and responsiveness.

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