Simple Guide to Azure Virtual Networks

Introduction

Azure Virtual Networks (VNet) are at the core of networking in Azure. They allow Azure resources to securely communicate with each other, the internet, and on-premises networks. Let’s break down all the key terms and features related to VNets in the simplest way possible.

What is an Azure Virtual Network?

A Virtual Network (VNet) is a logically isolated network in Azure where we can host and connect our resources, like virtual machines, securely.

Key Terms and Concepts

1. Subnet

   • A smaller network within a VNet.
   • Used to segment resources and control access.

2. Private IP Address

   • An IP address for internal communication within a VNet.

3. Public IP Address

   • An IP address to make resources accessible from the internet.

4. Network Security Group (NSG)

   • Acts like a firewall, controlling traffic to and from resources in a subnet or network interface.

5. Route Table

   • Defines the routing rules for network traffic within a VNet.

6. Peering

   • Connects two VNets so resources can communicate as if they’re in the same network.

7. VPN Gateway

   • Used for secure connections between an on-premises network and an Azure VNet.

8. Azure ExpressRoute

   • A private, high-speed connection between our on-premises network and Azure (no internet involved).

9. DNS (Domain Name System)

   • Resolves domain names (like mywebsite.com) to IP addresses.

10. Azure Bastion

    • A secure way to connect to virtual machines without exposing them to the internet.

11. Service Endpoints

    • Connect specific Azure services to our VNet securely, bypassing the internet.

12. Private Endpoint

    • A private IP for Azure services to access them securely within a VNet.

13. DDoS Protection

    • Defends our applications from Distributed Denial of Service (DDoS) attacks.

14. VNet Integration

    • Lets App Services or Azure Functions access resources in a VNet.

How VNets Work

1. We create a VNet and define a CIDR block (e.g., 10.0.0.0/16) to allocate IP addresses.
2. Divide the VNet into subnets to organize resources (e.g., one subnet for web servers, another for databases).
3. Use NSGs to control which traffic is allowed or denied.
4. Set up a Route Table to manage how traffic flows within and outside the VNet.
5. If needed, connect the VNet to other networks using Peering, VPN Gateway, or ExpressRoute.

Common Scenarios for VNets

1. Isolated Application Hosting: Keep applications secure by hosting them in a private VNet.
2. Hybrid Networking: Connect on-premises networks with Azure using VPN Gateway or ExpressRoute.
3. Service Integration: Access Azure services privately with Service Endpoints or Private Endpoints.
4. Multi-Region Networking: Use VNet Peering to connect resources in different Azure regions.

Azure Virtual Network Features at a Glance

Benefits of Azure VNets

1. Security: Control traffic with NSGs, private IPs, and firewalls.
2. Scalability: Add more subnets or peer VNets as your needs grow.
3. Flexibility: Integrate on-premises networks, access Azure services securely, and design complex architectures.

Conclusion

Azure Virtual Networks are the foundation of Azure networking. They enable secure, scalable, and flexible communication between resources. Whether hosting applications, building hybrid networks, or connecting globally, VNets provide all the tools you need.