Before making any updates to the production environment, the best course of action is to perform the update in a development or testing environment. Upgrading to version 3.7, which is a minor update, is generally less risky and should be tested first to ensure compatibility and stability before considering the major update to version 4.1.

Differential backups grow larger each day because they copy all changes since the last full backup, making them slower to complete. Incremental backups copy only the changes since the most recent backup, allowing the process to finish more quickly and reducing performance impact on the server.

Application whitelisting is the practice of specifying an index of approved software applications or executable files that are permitted to be present and active on a computer system.
The goal of whitelisting is to protect computers and networks from potentially harmful applications.

This solution provides a cost-effective and highly available approach to meet the application's needs:
Reserved instances are a good fit for the ten midsize instances that run most of the day, as they are typically offered at a discounted rate and are guaranteed.
During peak hours, pay-as-you-go instances can be added to handle the additional six instances required. This ensures scalability without committing to additional reserved capacity for off-peak times, which helps in reducing costs.

Implementing volume snapshots is an effective solution for quick recovery from ransomware attacks and protecting data integrity and availability. Snapshots capture the state of a storage volume at a point in time and can be used to restore data quickly with minimal administrative overhead.