In a three-tier architecture, which component hosts the business logic and application code?

• A. Application server
• B. Web server
• C. Database server
• D. Load balancer

Answer: (A)

In a three-tier architecture, the business logic and application code run on the application server, which sits between the presentation layer and the data layer. The web server handles client requests and delivers UI content, but it defers dynamic processing to the application server where server-side code enforces business rules, coordinates workflows, and processes data. The database server is responsible for storing and retrieving data. A load balancer simply distributes traffic and does not execute business logic. Therefore, the component that hosts the business logic and application code is the application server.