Resource Group
Keeps the related Azure resources together so they can be managed and monitored as one deployment unit.
Cloud hosting
How this site is hosted.
Internet
Application GatewayNSG
Web subnetVM / scale setNSG
App subnetNSG
Database subnetNSG
NAT Gateway
Virtual Network
Provides the network boundary that lets the application, web, and database tiers communicate securely.
Network Security Groups
Controls allowed traffic at each subnet so that only the necessary connection paths remain open.
Ubuntu VM
Hosts the Node.js application on a small Linux virtual machine that can be managed with PM2 and Nginx.
NAT Gateway
Allows outbound internet access for the private subnet while keeping the internal architecture more secure.
Application Gateway
Routes traffic to the web application and acts as the public entry point for incoming requests.
Virtual Machine Scale Set
Lets the application scale horizontally so multiple instances can handle more traffic when the load increases.