You are a software engineer and creating a serverless application in AWS to process photos. When each image is uploaded to an S3 bucket, a Lambda function is invoked. This Lambda function then calls Amazon Rekognition to detect text in the image. The returned results are saved in a DynamoDB table. You have used a template provided by AWS Serverless Application Model (AWS SAM) to build and deploy the whole application. For the above mentioned AWS services, which one do you still need to pay even if the service is not used?

Answer options:

A.Lambda function
B.SAM Template
C.API Gateway
D.Rekognition Image Analysis
E.None of the above

Correct Answer – E
AWS has provided a variety of services that customers only pay for the amount that they use (Pay-as-you-go model), which means that customers are not charged if services are unused. The document https://aws.amazon.com/pricing/?nc2=h_ql_pr is an introduction of AWS pricing features.
Option A is incorrect: Because the Lambda function created by SAM has used a Pay-as-you-go model, and there is no charge if it is not used.
Option B is incorrect: Because SAM Template is an extension to the CloudFormation template. No charge for the SAM service.
Option C is incorrect: Because users pay only for the API calls received and the amount of data transferred out for API Gateway.
Option D is incorrect: Because AWS Rekognition Image Analysis is charged based on the number of images analyzed.
Option E is CORRECT: Because all the above options do not have an upfront or monthly fee, and customers are not charged if the services are not used.