Amazon AWS Certified Solutions Architect Associate 2018 Set 4

A customer has written an application that uses Amazon S3 exclusively as a data store. The application works well until the customer increases the rate at which the application is updating information. The customer now reports that outdated data occasionally appears when the application accesses objects in Amazon S3.
What could be the problem, given that the application logic is otherwise correct?

A Solutions Architect is designing an architecture for a mobile gaming application. The application is expected to be very popular. The Architect needs to prevent the Amazon RDS MySQL database from becoming a bottleneck due to frequently accessed queries.
Which service or feature should the Architect add to prevent a bottleneck?

A company is launching an application that it expects to be very popular. The company needs a database that can scale with the rest of the application. The schema will change frequently. The application cannot afford any downtime for database changes.
Which AWS service allows the company to achieve these objectives?

A website experiences unpredictable traffic. During peak traffic times, the database is unable to keep up with the write request.
Which AWS service will help decouple the web application from the database?

A legacy application needs to interact with local storage using iSCSI. A team needs to design a reliable storage solution to provision all new storage on AWS.
Which storage solution meets the legacy application requirements?

A Solutions Architect is designing an application that will encrypt all data in an Amazon Redshift cluster.
Which action will encrypt the data at rest?