Here’s a clean GitHub-ready aws-architecture-flow.md Markdown file based on your content. You can paste this directly into a repo.

AWS Web Architecture – Step-by-Step Flow

1. User enters domain

The request starts with DNS handled by Amazon Route 53.

Example:

example.com → ALB

Route53 resolves the domain name to the Application Load Balancer (ALB) address.

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2. Internet traffic enters AWS

Traffic reaches the VPC through the Internet Gateway attached to the Amazon VPC.

Inside the VPC we typically separate resources into:

• Public Subnet
• Private Subnet

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3. Public subnet layer

Public subnets contain internet-facing components such as:

• Application Load Balancer (ALB)
• NAT Gateway

Example route table for a public subnet:

0.0.0.0/0 → Internet Gateway

This allows resources in the subnet to communicate with the internet.

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4. Load balancer distributes traffic

The load balancer sends traffic to backend servers running on Amazon EC2.

Example request flow:

User request ↓ ALB ↓ EC2 instance 1 EC2 instance 2 EC2 instance 3

This improves:

• Availability
• Scalability
• Fault tolerance

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5. Private subnet (application layer)

Application servers are usually placed in private subnets.

Reason:

Security

These servers should not be reachable from the internet directly.

Traffic flow:

ALB → EC2

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6. Database layer

The database (often Amazon RDS) sits in private subnets as well.

Example security rule:

RDS inbound: Port 3306 from EC2 security group

This ensures the database cannot be accessed directly from the internet.

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7. Private servers accessing the internet

Private servers still need to:

• Download updates
• Install packages
• Call external APIs

They use a NAT Gateway for outbound access:

EC2 → NAT Gateway → Internet

NAT allows outbound traffic only, blocking inbound connections from the internet.

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Final Architecture Flow

User ↓ Route53 ↓ Internet ↓ ALB (public subnet) ↓ EC2 Auto Scaling (private subnet) ↓ RDS database

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Key Design Principle

Production systems typically follow three layers:

Edge layer → Load Balancer Application layer → EC2 Data layer → Database

Each layer is isolated and secured.

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Layered Security Model

Security in AWS is implemented in multiple layers:

NACL ↓ Security Groups ↓ Application Firewall

This defense-in-depth strategy protects the infrastructure from multiple attack vectors.

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Summary

A typical secure AWS architecture includes:

• VPC network isolation
• Public and private subnets
• Load balancing
• Auto scaling compute
• Secure database access
• Controlled outbound internet via NAT

This design provides:

• High availability
• Scalability
• Security