You use DynamoDB to store the customer banking data. You need to create an audit log of all changes to the data. It’s important not to lose any information. What is an elegant way to accomplish this?

Answer options:

A.Use a DynamoDB Stream and stream all changes to AWS Lambda. Log the changes to AWS CloudWatch Logs, removing sensitive information before logging.
B.Before writing to DynamoDB, do a pre-write acknowledgment to disk on the application server, removing sensitive information before logging. Periodically rotate these log files into S3.
C.Use a DynamoDB Stream and periodically flush to an EC2 instance store, removing sensitive information before putting the objects. Periodically flush these logs to S3.
D.Before writing to DynamoDB, do a pre-write acknowledgment to disk on the application server, removing sensitive information before logging. Periodically pipe these files into CloudWatch Logs.

Answer-A
You can use the DynamoDB table streams as triggers to execute the lambda functions. Triggers are custom actions you take in response to updates made to the DynamoDB table. To create a trigger, first you enable Amazon DynamoDB Streams for your table. Then, you write a Lambda function to process the updates published to the stream.
For more information on DynamoDB with Lambda, please visit the below URL:
http://docs.aws.amazon.com/lambda/latest/dg/with-ddb.html