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Top 23 AWS Lambda Interview Questions and Answers

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AWS Lambda is a serverless computing service that allows developers to run code without provisioning or managing servers. It is an event-driven technology and enables developers to build and run applications with no server maintenance. It is a powerful tool that helps developers to build and deploy applications with ease.

AWS Lambda enables developers to quickly create APIs, mobile applications, and web applications that are reliable, scalable, and cost-effective. The service provides a wide range of features such as event-driven, highly scalable, and lower operational costs.

Job Interview

As the demand for AWS Lambda increases, employers are looking for skilled developers to fill their vacant positions. Interviews are a crucial part of the recruitment process, and employers are looking for candidates who are well versed in the technology. To ensure that you make a great impression, it is important to be well prepared for the interview.

This blog provides a comprehensive list of AWS Lambda interview questions and answers that can help you prepare for your upcoming job interview. From basic AWS Lambda concepts to advanced topics, these questions and answers cover everything that employers may be looking for. With these questions and answers, you can build a solid foundation and showcase your knowledge of the technology.

Thus, this blog post provides a detailed guide on AWS Lambda interview questions and answers. With this information, you can confidently ace your job interview and get closer to landing the job you desire.

Overview of AWS Lambda Interview Process

The AWS Lambda interview process typically involves a few key steps. First, the employer will review your submitted resume and application materials and decide to offer you an interview. This is generally done over a phone call or video chat, in which an interviewer will ask you questions about your background and experience, and discuss the job duties and expectations you would have as an AWS Lambda Developer.

Once the initial interview is complete, you may be asked to complete a technical test or coding challenge. This assessment is designed to evaluate your skills and knowledge with AWS Lambda, and may include coding a sample application, testing a feature, or debugging a problem.

If you pass the initial interview and technical test, you may be invited to the next round, which is usually the onsite interview. Here, you will meet with a team of people who will ask you more in- depth technical questions about AWS Lambda and the position. This is also an opportunity for the employer to get to know you better and decide if you are the right fit for the role.

Depending on the position and company, the final round may be a short presentation in which you showcase your knowledge of AWS Lambda and give examples of how you could solve their problem with the technology. If you successfully pass this stage, the employer will likely make you an offer and you can begin your new role as an AWS Lambda developer.


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Top 23 AWS Lambda Interview Questions and Answers

1. What is AWS Lambda?

AWS Lambda is a serverless computing service offered by Amazon Web Services (AWS). It is an event-driven, compute service which runs your code in response to certain events and automatically manages the compute resources required by that code. It allows you to focus on writing an application logic and not worry about managing and provisioning the underlying infrastructure. It automatically scales the application based on the incoming request and can instance the code in multiple regions in order to improve latency of the application. It supports multiple languages like Node.js, Java, Python, and C#/.NET.

2. What are the advantages of using AWS Lambda?

AWS Lambda offers several advantages over traditional server-based computing. For example, it eliminates the need to provision, manage and scale servers. It also eliminates operational overhead since there is no need to install and maintain software on the server or manage any server related tasks, such as security patching or OS upgrades. It also provides built-in monitoring and logging, making it easy to track and debug errors. Furthermore, AWS Lambda supports multiple languages and can be used to build serverless applications such as web, mobile and IoT applications.

3. What are the limitations of AWS Lambda?

AWS Lambda has certain limitations that should be taken into consideration when designing applications. For example, the maximum execution duration of a Lambda function is 5 minutes, and the maximum memory size is 3GB. Additionally, the size of the package that is uploaded to Lambda must be less than 50MB. Furthermore, Lambda functions can only be triggered by AWS services, such as Amazon S3, Kinesis, or API Gateway.

4. How does AWS Lambda work?

AWS Lambda works by invoking a function with a request. When an event or request is triggered, AWS Lambda is notified and begins to invoke the corresponding function. It then creates an instance of the function, allocates resources (memory, disk space, etc.), and executes the code. When the code completes execution, it returns the response to the client and releases the resources.

5. What triggers AWS Lambda?

AWS Lambda can be triggered by a variety of events from other AWS services. Some examples of events that can trigger Lambda functions are changes in an Amazon S3 bucket, an event from Amazon Kinesis, or an API call from Amazon API Gateway. Additionally, Lambda functions can also be manually invoked via the AWS console or CLI.

6. What languages are supported by AWS Lambda?

AWS Lambda supports multiple programming languages, including Node.js, Java, Python, and C#/.NET. Additionally, support for other languages, such as Go and Ruby, is currently in preview.

7. What is the best way to debug an AWS Lambda function?

The best way to debug an AWS Lambda function is to use the AWS Lambda console, which allows you to view the function logs in real time. Additionally, the console also provides a debugging tool that allows you to step through the code, set breakpoints, and inspect variables.

8. What is the AWS Lambda free tier?

The AWS Lambda free tier provides you with 1 million requests and 400,000 GB-seconds of compute time per month. This free tier is ideal for testing and development.

9. How is AWS Lambda different from Amazon EC2?

Amazon EC2 is an Infrastructure as a Service (IaaS) offering from Amazon Web Services. It provides customers with on-demand access to virtualized computing resources, such as servers, storage, and networking. AWS Lambda, on the other hand, is a Function as a Service (FaaS) offering, which provides customers with access to serverless computing resources. Additionally, AWS Lambda automatically manages and scales the resources required to run code in response to events, instead of requiring customers to manually provision resources.

10. How do I choose the right memory size for my AWS Lambda function?

The memory size of an AWS Lambda function determines the amount of memory allocated to the function and affects the execution time and cost of the function. The optimal memory size for a Lambda function can be determined by testing different sizes and monitoring the execution time and cost of each function.

11. What is a cold start in AWS Lambda?

A cold start in AWS Lambda is the time it takes for the function to be invoked, allocated the necessary resources, and begin executing the code. Cold starts can occur when the function has not been invoked for some time, or when the function is invoked for the first time.

12. How does AWS Lambda scale?

AWS Lambda automatically scales the application based on the incoming request and can instance the code in multiple regions. When the function is triggered, Lambda creates an instance of the function and allocates the necessary computing resources. As more requests are made, Lambda will increase the number of instances of the function, up to a maximum of 1000 instances.

13. What are the different pricing models for AWS Lambda?

AWS Lambda offers two pricing models – pay-per-request and reserved concurrency. The pay-per-request model is based on the number of requests made to the function and the duration of execution. In the reserved concurrency model, customers pay a flat fee for a predetermined concurrency level, which allows them to reserve a certain number of concurrent executions.

14. How can I reduce the cost of AWS Lambda?

There are several ways to reduce the cost of AWS Lambda. For example, by selecting the right memory size for your function, you can reduce the execution time and cost of your function. Additionally, you can choose the right pricing model for your usage pattern, such as the reserved concurrency model, which can reduce the cost of high-usage functions. Lastly, using services such as AWS CloudWatch and AWS X-Ray can help reduce the cost of monitoring and debugging your functions.

15. What is AWS Lambda Layers?

AWS Lambda Layers is a feature of AWS Lambda that allows customers to centrally manage code and data that is shared across multiple functions. This feature makes it easier to manage code and data that is used by multiple functions, as well as making it easier to update the shared code and data without having to update each function individually.

16. How is AWS Lambda different than traditional server-based applications?

AWS Lambda functions are event-driven and can be triggered by events from other AWS services, such as Amazon S3 and Amazon Kinesis, as well as from custom applications. This allows developers to quickly create, test, and deploy applications without worrying about server provisioning or managing resources. Additionally, Lambda functions can be written in a variety of languages and do not need to be maintained or updated manually.

17. What are the benefits of using AWS Lambda?

The main benefits of using AWS Lambda are scalability, cost-efficiency, and flexibility. AWS Lambda automatically scales up or down based on the number of requests it receives, so developers don’t have to worry about provisioning or managing servers. Lambda functions are also cost-effective because developers only pay for the time their functions are running and the requests they receive. Lastly, Lambda functions are highly flexible and can be written in a variety of languages, allowing developers to quickly create, test, and deploy applications.

18. What are the key components of AWS Lambda?

The key components of AWS Lambda include the following:

  • Lambda functions: These are the actual functions that run when triggered by an event or request.
  • Event sources: This is the source of the event that triggers the Lambda function. Common event sources include Amazon S3, Amazon Kinesis, and custom applications.
  • Execution environment: This is the environment in which the Lambda function runs, including the language runtime, memory, and other configurations.
  • Logging: This is the ability to log the execution of a Lambda function, including errors, for debugging purposes.

19. What programming languages can I use with AWS Lambda?

AWS Lambda supports a variety of programming languages including Java, Node.js, Go, Python, and C#.

20. How do I invoke a Lambda function?

A Lambda function can be invoked in a number of ways. It can be triggered by an event from another AWS service such as Amazon S3, Amazon Kinesis, or a custom application. It can also be invoked directly via the AWS Command Line Interface (CLI) or the AWS SDK.

21. What is the AWS Lambda pricing model?

AWS Lambda functions are charged based on the number of requests they receive and the duration of the execution. The duration is measured in increments of 100 milliseconds and billed per million requests.

22. What are the key features of AWS Lambda?

AWS Lambda offers a number of features, including:

  • Automatically scaling: Lambda automatically scales up or down based on the number of requests it receives.
  • Cost-efficiency: Lambda functions are billed based on the number of requests and duration of execution.
  • Event-driven: Lambda functions can be triggered by events from other AWS services or custom applications.
  • Flexibility: Lambda functions can be written in a variety of languages and do not need to be maintained or updated manually.
  • Security: Lambda provides a secure execution environment.

23. What is the Cold Start problem in AWS Lambda?

The Cold Start problem is an issue that occurs when a Lambda function has been idle for an extended period of time or has not been used recently. When this happens, it takes longer for the function to start, resulting in slower response times. The Cold Start problem can be addressed by using warm-up requests, which are periodic requests made to the function to keep it “warm” and ready to respond quickly to requests.

Tips on Preparing for a AWS Lambda Interview

  1. Become familiar with the AWS Lambda service, including its features and capabilities.
  2. Prepare a portfolio of projects that demonstrate your AWS Lambda knowledge and experience.
  3. Research common AWS Lambda interview questions and practice your answers.
  4. Get comfortable with the AWS management console and tooling.
  5. Understand the differences between serverless and traditional cloud architectures.
  6. Review the Lambda pricing model and understand the most cost- effective ways to use the service.
  7. Understand Lambda’s scalability and security benefits.
  8. Become familiar with the different programming languages and frameworks used to develop Lambda functions.
  9. Be able to explain how to debug and troubleshoot Lambda- based applications.
  10. Know how to use the AWS Lambda environment variables and other features.
  11. Practice deploying and managing Lambda functions using the AWS console or other DevOps tools.
  12. Read up on the most recent improvements to AWS Lambda.
  13. Develop your ability to explain the various use cases for Lambda.
  14. Understand the use of Lambda and other serverless technologies in the enterprise.
  15. Practice writing code snippets that demonstrate your Lambda knowledge.


In conclusion, the AWS Lambda service is a powerful and versatile tool that can help businesses increase efficiency and cost- effectiveness. With the right preparation, you can be sure to ace your AWS Lambda interview. By familiarizing yourself with the AWS Lambda service and the most common interview questions, you’ll be able to demonstrate your knowledge of the platform and make a great impression on the hiring team. With practice, you’ll be able to confidently answer any AWS Lambda- related questions thrown your way.