Answer: Application optimization

## Explanation When using Amazon RDS (Relational Database Service), AWS manages the underlying infrastructure, which means: - **Hardware lifecycle management** - Managed by AWS - **Server maintenance** - Managed by AWS (including OS patching, database engine updates) - **Power, network, and cooling provisioning** - Managed by AWS as part of the physical infrastructure However, **application optimization** remains the customer's responsibility because: - Application code optimization - Database schema design - Query performance tuning - Application-level security - Business logic implementation This follows the AWS Shared Responsibility Model where AWS manages the infrastructure layer, while customers are responsible for what they put in the cloud, including application-level configurations and optimizations.

Author: Ritesh Yadav