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AWS Lambda Interview Questions

AWS Lambda interview questionnaire 2018

There are many opportunities in the field of server-less computing, waiting for the correct candidate. With the market share of about 44%, AWS Lambda is one of the best servers-less computing platforms in the world. It has lots of benefits like for instance, no managing of servers, continuous scaling and sub-second metering. It has lots of opportunities to be discovered with significant returns.

It is a big platform and with lots of job perspective also.  With so many languages to be catered, it has jobs ranging from system engineer to IOT Architect and cloud support associate. Thus, every year some fresher and experience holders try to face the interview and landing job as a server-less computing expert. There are lots of opportunities up for grab in AWS Lambda Development.

We help you with a set of questions that can come up in AWS Lambda interview 2018:

Q1. What does AWS Lambda mean?

Ans. AWS Lambda is one the best compute service in the market, which is serverless. It allows you to run codes without the help of managing servers or provisioning. You have to pay for the computing time when you consume data. There are no charges to be paid when you are not running your code. Using Lambda, you can quickly run codes for any application or backend service virtually, without any administration. You have to upload the code and rest everything is taken care of by Lambda. Lambda runs and scales your code with high availability. You can even set the code up to trigger from the other AWS available or give it a call directly from the mobile app or any web.

Q2. What restrictions apply to AWS Lambda function code?

Ans. Lambda imposes very few restrictions on operating system activities and standard language. However, there are few of the activities that have been disabled like for instance, inbound network connections and trace calls, which is a debugging system, and TCP port 25 traffic as a measure to anti-spam. For outbound connections IP/TCP sockets are supportive.

Q3. How long can an AWS Lambda function execute?

Ans. The complete execution has to take place within 300 seconds from placing the calls to AWS Lambda. 3 seconds is the default timeout however you can set any timeout value between 1 to 300 seconds

Q4. How does AWS Lambda secure my code?

Ans. What Labda does is, it stores the code in the Amazon S3 and encrypts it when it is resting. AWS Lambda is known to perform additional integrity check while the code is running.

Q5. On AWS Lambda what all kinds of code can run?

Ans. AWS Lambda offers you an easy way to get many activities done in the cloud. Like for instance, AWS Lambda can be used to build mobile back-ends from Amazon DynamoDB to retrieve and transform data. Handlers that transform and compress objects as they get uploaded to Amazon S3, using Amazon Kinesis the server-less processing of streaming data, and reporting and auditing of the API calls that are made to any Web Services of Amazon are other activities can be done in the cloud with the help of AWS Lambda.

Q6. What is the definition of Auto-Scaling?

Ans. It is a feature available in the Web services of Amazon that helps you enable to spin and configure the novel instances automatically. At any stage, you don’t have to interfere, and one can quickly do the monitoring using thresholds and metrics. You merely have to cross the threshold to enable the task and instances without any interference that may have increased horizontally.

Q7. Which all languages are supported by AWS Lambda?

Ans. AWS Lambda supports the codes that are written in Python, C# (.NET Core), Node.js (JavaScript), Java (Java 8 compatible), and Go. The code can also include existing libraries and even the native ones.

Q8. Is the infrastructure accessible on which the AWS Lambda runs?

Ans. No. As AWS Lambda starts operating the compute infrastructure on behalf of the user,  the foundation on which AWS Lambda runs is not accessible. It allows Lambda to apply security patches, perform health checks, and work out other routine maintenance.

Q9. Can I use packages with AWS Lambda?

Ans. Absolutely yes! You can efficiently use custom as well as NPM packages to be precise.

Q10.  Are AWS Lambda functions available and to what extent?

Ans. AWS Lambda has been so designed to use redundancy and replication so that it provides high availability for both, lambda functions it operates on and the service it provides. Maintenance windows and scheduled downtimes for Lambda functions.

Q11.  On a functional level is there any default limit to be applied?

The default limit is applicable only at the account level. So no, there is no default limit applied at a functional level.

Q12.  How can a serverless application be automated?

Ans. The server-less application’s release process can be automated by using an AWS CodePipeline and also an AWS CodeDeploy.  The CodePipeline is a continuous form of delivery service that is enabled with modeling, visualizing and automating the steps that are required, so that server less application can be released. CodeDeploy also comes with a deployment engine that is automated for Lambda-based applications. It lets you coordinate deployments as per the best-practice methodologies established like a canary and linear deployment, and assists you to develop significant barriers to ensure that the newly-deployed program is secure, stable, and ready for industrial use.

Q13.  How can a serverless application be started?

Ans. For getting started, the console of AWS Lambda has to be visited, and a blueprint has to be downloaded. The file downloaded will have an AWS SAM file (which is used to define AWS resources in the application), and a.ZIP file (which includes the function’s code). The AWS CloudFormation commands can then be used for packaging and deploying the serverless application just downloaded. For further details, visit the documentation.

Q14.  How do I troubleshoot a serverless application?

Ans. Lambda function can be enabled for tracking, with AWS X-Ray by addition of X-Ray permissions to Lambda function’s role of execution and changing the function’s “mode of tracing” to “active.” When you enable X-ray for Lambda function, AWS Lambda shall emit the tracing information to X-Ray with information about the Lambda service that incurred while invoking the function. This shall provide you with information such as the overhead of Lambda service, the function unit time, and time for function execution. Also, the X-Ray SDK can be included in Lambda deploying the package to create one’s segments of the trace, annotate one’s marks, or view the trace segments for various downstream calls that are made from Lambda function. X-Ray SDKs are presently available for Node.js and Java. Visit the Troubleshooting applications based on Lambda to learn more. AWS X-Ray rates shall apply.

Q15.  Do the AWS Lambda-based functions stay available when code or its configuration is changed?

Ans. Yes. When a Lambda function is updated, there shall be a brief period, less than a minute, when requests can be served by either the old or the new version of the function.

Q16.  Is there any limit to the quantity of AWS Lambda functions that can be executed at once?

Ans. No. The AWS Lambda is designed so that it can run some instances of functions simultaneously. However, AWS Lambda has a by default safety threshold for some consecutive runs for every account per region. The maximum successive executions for single AWS Lambda functions can be controlled which can be used to reserve a portion of the account concurrency threshold for the critical functions or lower traffic rates to downstream the resources.

If you so wish to submit a query to increase the limit, you can refer to the Support Centre for more.

Q17.  What happens when my account surpasses the default threshold limit on the executions?

Ans. Upon exceeding the threshold limit, the AWS Lambda functions are being called synchronously and will return a threshold error (429 error- code). The tasks of Lambda functions that are called asynchronously shall absorb the reasonable traffic bursts for 15-30 minutes, after which the incoming events shall be rejected as they are throttled. In case the Lambda function is being called in response to the Amazon S3 events, events that are rejected by AWS Lambda may be retained back and retried by S3 for 24 hours. The events coming from streams of Amazon Kinesis and Amazon DynamoDB are retried along as the Lambda function doesn’t succeed, or the data doesn’t expire. Amazon Kinesis and Amazon DynamoDB Streams hold the data for 24 hours.

Q18.  What is a server-less application?

Ans. The applications which are Lambda-based (are also referred to as the server-less applications) are made of functions that are triggered by various events. A default server-less application consists of one or more of such functions that are triggered by the events such as object upload to Amazon S3, Amazon SNS, or API actions. The functions can work alone or make use of other resources like DynamoDB tables or buckets of Amazon S3. The most default serverless application is a function.

 Q19.  What advantages can we have by using Server-less approach?

Ans. Firstly, this approach has simple operations which provide quick time to market and better sales. Users need to only pay for when the code is compiling, and many costs can be saved by enhancing the profits. Also, managing the components of the broader application is not a big deal. In addition to this, it is not needed to have the additional infrastructure. The most significant benefit is that consumers do not need to worry about the servers on which the code is executed.

Q20.  What is the Disadvantage of using this approach?

Ans. Everything comes with its own merits and demerits depending on the task performed. Coming to the server-less approach, this fact is applicable here as well. In a few cases, their upper limit is strictly on the vendor control in this approach, and this means more downtime and thus more losses. The loss of system functionality and the system’s limits are other issues. Also to mention, no dedicated hardware is available for the server-less approach. Thus performance and security have become essential challenges at various stages. Sometimes errors by the customer can also give rise to the problems. New deployments, as well as the monitoring tools, have become the sole choice when the matter is of converting to functions of Google Cloud.

With other AWS services and AWS Lambda, powerful applications can be built by developers that can scale up and down automatically and run on highly available platforms. There are job opportunities open for various posts like automation testing with AWS Lambda, lead architect in AWS IOT Lambda script and so on. With above content, you can sure get an idea of questions that may come your way in the interview.