AWS Lambda interview questions

71. Can I change the version of Amazon Linux or any language runtime?
No. AWS Lambda offers a single version of the operating system and managed language runtime to all users of the service. You can bring your own language runtime to use in Lambda.

72. Do my AWS Lambda functions remain available when I change my code or its configuration?
Yes. When you update a Lambda function, there will be a brief window of time, typically less than a minute, when requests could be served by either the old or the new version of your function.

73. Is there a limit to the number of AWS Lambda functions I can execute at once?
No. AWS Lambda is designed to run many instances of your functions in parallel. However, AWS Lambda has a default safety throttle for number of concurrent executions per account per region . You can also control the maximum concurrent executions for individual AWS Lambda functions which you can use to reserve a subset of your account concurrency limit for critical functions, or cap traffic rates to downstream resources.

74. What happens if my account exceeds the default throttle limit on concurrent executions?
On exceeding the throttle limit, AWS Lambda functions being invoked synchronously will return a throttling error (429 error code). Lambda functions being invoked asynchronously can absorb reasonable bursts of traffic for approximately 15-30 minutes, after which incoming events will be rejected as throttled. In case the Lambda function is being invoked in response to Amazon S3 events, events rejected by AWS Lambda may be retained and retried by S3 for 24 hours. Events from Amazon Kinesis streams and Amazon DynamoDB streams are retried until the Lambda function succeeds or the data expires. Amazon Kinesis and Amazon DynamoDB Streams retain data for 24 hours.

75. How do I enable and disable the VPC support for my Lambda function?
To enable VPC support, you need to specify one or more subnets in a single VPC and a security group as part of your function configuration. To disable VPC support, you need to update the function configuration and specify an empty list for the subnet and security group. You can change these settings using the AWS APIs, CLI, or AWS Lambda Management Console.

76. Can a single Lambda function have access to multiple VPCs?
No. Lambda functions provide access only to a single VPC. If multiple subnets are specified, they must all be in the same VPC. You can connect to other VPCs by peering your VPCs.

77. How do I configure my Lambda functions to enable code signing?
You can enable code signing by creating a Code Signing Configuration through the AWS Management Console, the Lambda API, the AWS CLI, AWS CloudFormation, and AWS SAM. Code Signing Configuration helps you specify the approved signing profiles and configure whether to warn or reject deployments if signature checks fail. Code Signing Configurations can be attached to individual Lambda functions to enable the code signing feature. Such functions now start verifying signatures at deployment.

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