Azure Virtual Network Basics – Public vs Private Networks
Azure Virtual Network Basics – Public vs Private
If you’re getting started with Azure Networking, the first concept you must master is the Virtual Network (aka VNet). This is the foundation of all networking in Azure.
What is a VNet?
A Virtual Network (VNet) in Azure is like your private data center network in the cloud. It allows Azure resources (like VMs, App Services, etc.) to communicate with each other securely. Think of it like a virtual version of a LAN (Local Area Network).
Public vs Private Networking
Private Network
- Resources inside a VNet don’t have internet access by default.
- Private IPs like
10.x.x.x,172.16.x.x, or192.168.x.x - Used for internal apps, databases, backend services
Public Network
- When you assign a Public IP to a VM or Load Balancer
- Accessible from the internet
- Needs NSGs and firewalls for protection
IP Addressing in Azure
When you create a VNet, you define an IP address space (CIDR block):
Example:
- VNet CIDR:
10.0.0.0/16→ gives you 65,536 IPs - Subnet A:
10.0.1.0/24 - Subnet B:
10.0.2.0/24
Azure reserves 5 IPs per subnet (first 4 + last 1) — plan your space accordingly.
Internet Access
- Outbound: By default, VMs can access the internet for updates, downloads.
- Inbound: You must assign a Public IP or use a Load Balancer for external access.
Tip
Just because your VM has internet access, doesn’t mean it’s public. Internet outbound is default; inbound needs explicit public IP and NSG rule.
Learn More
Next up: Hub-Spoke and VNet Peering!
– Kasi @ KasdevTech or LinkedIn