AWS Certified Solutions Architect – Professional — Question 78

You are developing a new mobile application and are considering storing user preferences in AWS.2w This would provide a more uniform cross-device experience to users using multiple mobile devices to access the application. The preference data for each user is estimated to be 50KB in size Additionally 5 million customers are expected to use the application on a regular basis.
The solution needs to be cost-effective, highly available, scalable and secure, how would you design a solution to meet the above requirements?

Answer options

• A. Setup an RDS MySQL instance in 2 availability zones to store the user preference data. Deploy a public facing application on a server in front of the database to manage security and access credentials
• B. Setup a DynamoDB table with an item for each user having the necessary attributes to hold the user preferences. The mobile application will query the user preferences directly from the DynamoDB table. Utilize STS. Web Identity Federation, and DynamoDB Fine Grained Access Control to authenticate and authorize access.
• C. Setup an RDS MySQL instance with multiple read replicas in 2 availability zones to store the user preference data .The mobile application will query the user preferences from the read replicas. Leverage the MySQL user management and access privilege system to manage security and access credentials.
• D. Store the user preference data in S3 Setup a DynamoDB table with an item for each user and an item attribute pointing to the user' S3 object. The mobile application will retrieve the S3 URL from DynamoDB and then access the S3 object directly utilize STS, Web identity Federation, and S3 ACLs to authenticate and authorize access.

Correct answer: B

Explanation

Option B is correct because DynamoDB is designed for scalability and can efficiently handle high volumes of requests, making it suitable for the expected 5 million users. Options A and C involve RDS, which may not scale as easily as DynamoDB for such a large user base, and they also introduce additional complexity in managing databases. Option D complicates the architecture by introducing S3, which is not necessary when DynamoDB can handle the requirements directly.