Top AWS Lambda Interview Questions and Answers Mastering Serverless Computing

AWS stands for Amazon Web Services. It is a comprehensive and widely-used cloud computing platform provided by Amazon. AWS offers a vast array of services including computing power, storage solutions, databases, machine learning, analytics, security, and more, allowing businesses to build and deploy applications and services quickly and efficiently without the need to manage physical infrastructure.

Top 25 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 allows you to run code in response to events without provisioning or managing servers. Lambda automatically scales your application by running code in response to triggers, such as changes to data in Amazon S3 buckets or updates to DynamoDB tables.

2. What are the languages supported by AWS Lambda?

AWS Lambda supports multiple programming languages, including:

  • Node.js
  • Python
  • Java
  • C#
  • Go

3. What is automated deployment?

Automated deployment is the process of automatically deploying code changes to a server or cloud environment without manual intervention. In the context of AWS Lambda, automated deployment can be achieved using CI/CD (Continuous Integration/Continuous Deployment) pipelines, which automate the build, test, and deployment process.

4. What is auto-scaling in Lambda?

Auto-scaling in Lambda refers to the ability of the service to automatically scale the number of concurrent executions of your functions based on the incoming request rate. Lambda manages the infrastructure required to run your code, allowing it to scale seamlessly in response to changes in demand.

5. What type of storage is provided by Amazon?

Amazon provides various types of storage services, including:

  • Amazon S3 (Simple Storage Service) for object storage.
  • Amazon EBS (Elastic Block Store) for block-level storage volumes.
  • Amazon EFS (Elastic File System) for scalable file storage.

6. While performing DDOS, what is the limit for execution in Lambda?

During a Distributed Denial of Service (DDOS) attack, Lambda functions are subject to service limits imposed by AWS. The default limit for concurrent executions can vary based on the region and account configuration. However, AWS allows you to request a limit increase if needed.

7. What do you think makes Lambda a time-saving approach?

Lambda eliminates the need to provision and manage servers, allowing developers to focus on writing code rather than managing infrastructure. Its serverless architecture automatically handles scaling, fault tolerance, and high availability, saving time and effort in deployment and operations.

8. What is your understanding of AMI?

AMI stands for Amazon Machine Image. It is a template that contains the software configuration (operating system, application server, and applications) required to launch an EC2 instance. AMIs are used to create virtual servers in the Amazon Elastic Compute Cloud (EC2) service.

9. Do you think there is a relationship between Instances and AMI?

Yes, there is a relationship between instances and AMIs. An instance is a virtual server running in the AWS cloud, while an AMI is a template used to launch instances. You can launch multiple instances from the same AMI, and instances launched from the same AMI will have identical configurations.

10. What are the best practices for security in Lambda?

Some best practices for security in Lambda include:

  • Applying least privilege principles by granting only necessary permissions to Lambda functions.
  • Encrypting sensitive data using AWS Key Management Service (KMS).
  • Monitoring and logging Lambda function invocations using AWS CloudWatch Logs.
  • Implementing network security measures such as VPC (Virtual Private Cloud) configurations and security groups.

11. How does AWS Lambda pricing work?

AWS Lambda pricing is based on the number of requests and the duration of execution. You pay only for the compute time consumed by your function and the number of requests processed. There are no upfront fees or minimum charges, and you are not charged when your code is not running.

12. What are the different types of triggers supported by AWS Lambda?

AWS Lambda supports various triggers, including:

  • API Gateway
  • S3 (Simple Storage Service)
  • DynamoDB Streams
  • SNS (Simple Notification Service)
  • CloudWatch Events
  • Kinesis Streams

13. Can you use AWS Lambda with other AWS services?

Yes, AWS Lambda can be integrated with other AWS services to build serverless architectures. You can use Lambda functions to process events and triggers from services such as S3, DynamoDB, SQS, SNS, and more, enabling seamless automation and event-driven workflows.

14. What is the maximum execution time for a Lambda function?

The maximum execution time for a Lambda function is 15 minutes. If a function runs for longer than this limit, it will be terminated by Lambda. It is important to design your functions to complete within this time constraint, or consider breaking down longer tasks into smaller, more manageable units.

15. How does AWS Lambda handle concurrency?

AWS Lambda automatically scales the number of concurrent executions of your functions in response to incoming requests. It manages the infrastructure required to run your code, provisioning resources as needed to handle the workload. You can configure concurrency limits to control the maximum number of concurrent executions.

16. What is the difference between synchronous and asynchronous invocation in Lambda?

Synchronous invocation means that the calling application waits for the Lambda function to complete and return a response. Asynchronous invocation, on the other hand, allows the calling application to continue executing without waiting for the function to complete. Lambda supports both synchronous and asynchronous invocation methods.

17. How can you monitor and troubleshoot Lambda functions?

You can monitor Lambda functions using AWS CloudWatch, which provides metrics and logs for monitoring function invocations, errors, and performance. Additionally, you can enable X-Ray tracing to gain insights into the performance and execution flow of your functions. Troubleshooting can be done by analyzing logs and metrics to identify and resolve issues.

18. What are the benefits of using AWS Lambda over traditional server-based architectures?

Some benefits of using AWS Lambda over traditional server-based architectures include:

  • Reduced operational overhead: Lambda manages the infrastructure, allowing developers to focus on code.
  • Cost-effectiveness: You pay only for the compute time consumed by your functions, with no upfront fees or minimum charges.
  • Scalability: Lambda automatically scales to handle incoming requests, ensuring high availability and performance.
  • Simplified deployment: With Lambda, you can deploy code changes quickly and easily without managing servers.

19. Can you run Docker containers in AWS Lambda?

No, AWS Lambda does not support running Docker containers directly. Lambda functions are executed within a managed runtime environment provided by AWS, and you cannot customize the underlying infrastructure. However, you can package and deploy your code along with its dependencies as a zip file or container image.

20. How can you optimize the performance of AWS Lambda functions?

You can optimize the performance of AWS Lambda functions by:

  • Reducing function execution time: Optimize code logic and minimize external dependencies to improve performance.
  • Implementing concurrency controls: Configure concurrency limits to prevent resource contention and ensure optimal throughput.
  • Leveraging caching: Use caching mechanisms such as AWS DynamoDB or Amazon ElastiCache to store and retrieve frequently accessed data.
  • Implementing asynchronous processing: Use asynchronous invocation to parallelize and distribute workload processing across multiple function instances.

21. What is cold start in AWS Lambda?

Cold start refers to the initialization time required to spin up a new execution environment for a Lambda function. When a function is invoked for the first time or after a period of inactivity, Lambda may need to create a new execution context, resulting in increased latency for the initial invocation. Cold starts can impact the responsiveness of serverless applications and should be considered during performance optimization.

22. How can you handle dependencies in AWS Lambda functions?

You can include dependencies in your AWS Lambda functions by packaging them along with your code. For languages such as Node.js and Python, you can use package managers like npm and pip to install dependencies locally and bundle them with your function code. Alternatively, you can use deployment packages or container images to include dependencies at deployment time.

23. What are Lambda layers?

Lambda layers are a way to centrally manage code and dependencies that are shared across multiple Lambda functions. You can create layers containing libraries, custom runtimes, or other dependencies and attach them to your functions. This allows you to reuse code and simplify maintenance across multiple functions.

24. How can you secure AWS Lambda functions?

You can secure AWS Lambda functions by:

  • Implementing IAM (Identity and Access Management) policies to control access to functions and resources.
  • Using VPC (Virtual Private Cloud) configurations to restrict network access and enhance security.
  • Encrypting sensitive data using AWS Key Management Service (KMS) or client-side encryption.
  • Applying best practices for securing code, such as input validation and parameterization, to prevent common security vulnerabilities.

25. What are some use cases for AWS Lambda?

AWS Lambda is commonly used for various use cases, including:

  • Real-time data processing and analysis
  • Event-driven automation and orchestration
  • File and data processing tasks
  • Backend services for web and mobile applications
  • IoT (Internet of Things) data processing and device control


By familiarizing yourself with these top AWS Lambda interview questions and answers, you’ll be well-equipped to tackle any interview scenario with confidence. Remember to understand the underlying concepts and principles behind each question, and practice explaining your answers concisely and effectively.

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