Step-by-Step: Designing an Azure Virtual Network (VNet)

Just as a physical network needs routers and switches, every Azure infrastructure is built on a virtual network — a VNet. This tutorial covers VNet fundamentals step by step.

What exactly does a VNet do?
A VNet is a private, isolated network inside Azure where resources like virtual machines, databases, and other services communicate with each other — just like a company's internal network, except it's entirely software-defined and hosted in a Microsoft data center.

Step 1: Creating a VNet and defining addressing
When creating a VNet, you need to specify an IP address range in CIDR format (e.g., 10.0.0.0/16) — the same subnetting concept taught in basic networking courses, just applied to a cloud environment this time.

Step 2: Subnetting
A VNet is rarely used on its own; it's divided into smaller subnets — for example, one subnet for web servers and a separate one for the database. This separation both simplifies management and forms the basis for applying distinct security rules per layer.

Step 3: Connecting a virtual machine to the VNet
When creating a VM in Azure, you need to specify which VNet and which subnet it belongs to. This is exactly equivalent to plugging a physical server into a specific switch port.

Step 4: Network Security Group (NSG)
An NSG is a set of allow/deny rules that control inbound and outbound traffic for a subnet or network interface — conceptually identical to an Access Control List (ACL) configured on Cisco routers and switches.

Step 5: VNet peering
If two separate VNets (say, for two different projects) need to communicate directly, instead of routing traffic over the public internet, VNet peering connects them directly and privately.

Step 6: Comparison with traditional networking
Everything done in a VNet — addressing, subnetting, access control — is exactly the same concepts taught in CCNA and MCSA courses; the main difference is that instead of cables and physical equipment, everything is defined through the portal or code.

Summary
A VNet is a bridge between the traditional networking knowledge you've already learned and the world of cloud — the exact knowledge that turns this path, for network engineers, into a natural next step rather than starting from zero.