Top 20+ AWS Lambda Interview Questions and Answers

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AWS Lambda Interview Questions

1. What is AWS Lambda?

Amazon Web Services (AWS) Lambda is a serverless compute service that runs your code in response to events and automatically manages the underlying compute resources for you. With Lambda, you can run code for virtually any type of application or backend service, all with zero administration.

Lambda automatically scales and monitors your applications, so you don’t have to. You only pay for the compute time that you consume. This makes it an attractive option for building and running microservices, data processing jobs, and real-time streaming applications.

2. What is Auto Scaling in Lambda?

It is one of the features of AWS that helps one to automatically configure and spin novel instances. One of the best things about AWS Auto Scaling is that it does not require any interference at any stage. However, users can monitor everything through metrics and thresholds. To enable this task, one needs to cross a threshold, and without interference, one can see the instances scaled horizontally.

3. What are the languages supported by AWS Lambda?

Amazon Web Services (AWS) Lambda supports the following languages:

  1. Node.js
  2. Java
  3. C#
  4. Go
  5. PowerShell
  6. Python
  7. Ruby
  8. .NET Core

You can use any of these languages to write your code for AWS Lambda. You can also use the AWS Serverless Application Model (SAM) to build and deploy your serverless applications in any of these languages.

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

You can now configure your AWS Lambda functions to run up to 15 minutes per execution. Previously, the maximum execution time (timeout) for a Lambda function was 5 minutes. Now, it is easier than ever to perform big data analysis, bulk data transformation, batch event processing, and statistical computations using longer-running functions.

  • You can now set the timeout value for a function to any value up to 15 minutes. When the specified timeout is reached, AWS Lambda terminates the execution of your Lambda function.
  • As a best practice, you should set the timeout value based on your expected execution time to prevent your function from running longer than intended.

5. What do you think makes Lambda a timesaving approach?

There can be a number of reasons behind this. One of which is that Lambda stores everything in local server memory.  Another reason can be that data is stored directly in the database without it affecting performance. In addition to these features, Lambda also has simple testing techniques; for example, integration testing can be made powerful through multiple vendors.

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

Using AWS IAM (Identity Access and Management) is one of the widely used security practices in Lambda. Granting specific user access to particular roles is another effective option to enhance security. In this security practice, access can be restricted to hosts that are not trusted or authorized. In addition to this, no matter how effective and stringent the security protocols are, they should always be updated timely.

7. What are the limitations of AWS Lambda?

Some of the limitations of AWS Lambda are as follows:

  • The default deployment package size is 50 MB.
  • The ephemeral disk space is limited to 512 MB as the Lambda function will take a longer time to execute with a larger package size.
  • The execution time is more when the memory allocation is less.
  • The memory range is from 128 MB to 10,240 MB.
  • The maximum execution timeout for a function is 15 minutes.

8. What is elastic blockage storage in Lambda?

Amazon’s elastic block storage (EBS) can be defined as a virtual storage area network where tasks can be started. It can tolerate faults easily, and users need not worry about loss of data even if the disk is damaged in the RAID. Provisioning and allocating the storage can also be done in EBS. If required, it can also be connected to an API.

9. How does Lambda handle failure during event processing?

If an AWS Lambda function fails during event processing, the function is retried. If the function continues to fail after multiple retries, it will be considered a failed execution.

By default, Lambda will retry the function for up to two times, with a delay between retries. You can configure the number of retries and the delay between retries using the AWS Management Console, the AWS CLI, or the AWS SDKs.

If the function continues to fail after the maximum number of retries, it will be considered a failed execution. You can set up notifications or alarms to be triggered when a function fails, so that you can take appropriate action to troubleshoot the issue.

10. Is vertical scaling possible in Lambda?

Yes, vertical scaling is possible in Lambda. Vertical scaling is one of the most in-demand features of AWS Lambda. This feature is generally used when a user needs to spin a larger instance. If in case, they are already using an instance, it can be paused and detached from the server. In this process, it is important to note the ID of the new device post that can continue the process.

AWS Lambda Interview Questions

11. How is a Lambda function executed?

An AWS Lambda function is executed in response to an event. When the event occurs, Lambda assigns the function to a compute resource and begins executing the function’s code.

The function is executed in a stateless environment, which means that it does not maintain any persistent state between executions. This allows Lambda to scale the function up or down based on demand, and to efficiently allocate compute resources to handle the workload.

After the function has completed executing, the compute resources are released and the function goes back into a dormant state until the next time it is needed. This allows you to run your code without having to worry about managing the underlying infrastructure.

12. Name a simple method to improve performance in AWS Lambda.

Performance in AWS Lambda can be simply improved by using RAID, the Linux software. It also helps in increasing security.

13. In how many ways can AWS Lambda be used?

One can use Lambda in the following ways:

As an event-driven computing service, AWS Lambda runs code in response to events.

These events can be the changes to data in an Amazon S3 bucket or AWS DynamoDB

Lambda can run code in response to HTTP requests using Amazon API Gateway or API calls made using AWS SDKs.

14. How does AWS Lambda secure my code?

Lambda secures the code by encrypting it. Lambda stores the code in Amazon S3 buckets and encrypts it when it is resting. Further, AWS Lambda performs an additional integrity check on the code while it is running.

Advanced AWS Lambda Interview Questions

15. What are the restrictions applied to the AWS Lambda function code?

Although AWS Lambda has very few restrictions on various kinds of operating systems activities and standard programming languages, there are a few restrictions on activities that disable instances and trace calls and inbound network connections. In addition to this, AWS Lambda also disables activities such as debugging systems and TCP ports. For outbound data connection, TCP or IP sockets are very supportive.

16. How to get started with a serverless application?

In order to get started with a serverless application, a user needs to console AWS Lambda and download the blueprint. The original file that will be downloaded should have an AWS Sam file, also known as AWS resource in the application, and a ZIP file. AWS Cloud formation commands can be used for packaging and deploying serverless application codes and documentation can also be performed.

17. What are the disadvantages of using the serverless approach?

Everything in AWS Lambda comes with its own merits and demerits depending on the task performed. The upper limit is strictly on the vendor control in the serverless approach and offers more downtime. Sometimes there is a loss of system functionality and the system’s limits are other issues; no dedicated hardware is available for AWS serverless approach. In most cases, customer errors can also give rise to problems.

18. What is the difference between an anonymous class and the Lambda function?

One of the biggest differences between an anonymous class and the Lambda function is the use of keywords. While the keywords in a Lambda function are used to resolve functional classes, the keywords in anonymous classes are used to resolve anonymous functional classes.

19. Is Lambda Expression a nameless suspension of code?

Yes, a lambda expression is a nameless suspension of code that can be treated as a value and passed around as a parameter or stored in a variable. It is a way to define a block of code as an anonymous function, which can be executed later.

Lambda expressions are a feature of functional programming languages, and they are often used to define callback functions or to create functional interfaces. In Java, for example, a lambda expression is a concise way to represent a functional interface (an interface with a single abstract method) as an instance.

Lambda expressions are a powerful and concise way to define and execute code, and they are widely used in modern programming languages such as Java, Python, and C#.

20. What kind of code can run on AWS Lambda?

There are many activities that can be performed on AWS Lambda; for example, it can be used to build mobile backends from Amazon DynamoDB to retrieve and transform data. Handlers transform and compress objects as they get uploaded to Amazon S3. This is done by using Amazon Kinesis, serverless processing of streaming data. The reporting and auditing of API calls can be made to any web service of Amazon, and many other activities can also be done with the help of AWS Lambda.

21. What are final variables and effectively final variables in Lambda?

Final variables are those that cannot be modified once assigned, while effectively final variables can be changed as they are in their earlier stage and have not been assigned a value. Effectively final variables play a huge role in testing as well. If final variables are to be equipped with several additional features, this can be done through effectively final variables.

22. How does AWS Lambda work?

Many people consider AWS Lambda to be a little confusing, but it is not. It is just a simple four-step process that begins with uploading code to AWS Lambda. The next step is to set up your code to trigger from other AWS services, HTTP endpoints, or mobile apps. AWS Lambda will only run a code when it is triggered and will only use the computing resources needed to run it.

23. What can one build with AWS Lambda?

The following is the list of what can one build with AWS Lambda:

  • Real-time file processing
  • Sorting real-time stream processing
  • Data processing
  • Data validation
  • Filtering
  • Third-party API requests

24. Do Lambda-based functions stay available after the code or configuration is changed?

Yes, Lambda-based functions remain available after the code or configuration is changed. When a Lambda function is updated, there is a brief period, less than a minute, when requests can be served by either the old or new version of the function.

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