What is 3 TIER APPLICATION:

A tier application setup divides an application into separate layers. Each layer performs a specific task, improving security, performance, and scalability.

Common 3-Tier Architecture Web Tier – Receives user requests Example: OCI Load Balancer or web server. Application Tier – Processes business logic Example: Compute instances running the application. Database Tier – Stores and retrieves data Example: Oracle Database or Autonomous Database.

Simple Example

When a customer places an order:

Customer → Load Balancer → Application Server processes order → Database stores order → Confirmation returns to customer

Security Design Load Balancer: Usually in a public subnet Application servers: Private subnet Database: Private subnet NSGs/Security Lists allow traffic only between the required tiers

Key benefit: The application and database remain protected from direct Internet access.