Microsoft Azure Virtual Network (VNet) Subnetting

VPC Subnetting Design & Sizing Reference Guide

Cloud Platform Name

Microsoft Azure Virtual Network (VNet)

Common Network Range

10.0.0.0/16

Subnet Partitioning Strategy

Azure VNet uses Address Spaces to allocate networks. Special subnets are required: GatewaySubnet (for ExpressRoute or VPN Gateways) and AzureFirewallSubnet. Do not deploy resources to these special subnets.

Recommended Subnet Mask Sizing

GatewaySubnet: /27 or /26 (Azure recommends /27 minimum). AzureFirewallSubnet: /26 minimum. Production Application Subnets: /24 (251 usable addresses after 5 reserved Azure IPs).

VPC Networking Sizing Principles

Virtual Private Clouds (VPC) form the isolation layer of cloud infrastructure. Proper planning of CIDR sizing prevents address space overlap, ensuring seamless hybrid connections to on-premises datacenters via VPN or dedicated trunks. Sizing application subnets correctly avoids resource exhaustion during high autoscaling demands.

How to configure this cloud VPC subnetwork

1. Define VNet Address Space

Create an Azure Virtual Network allocating 10.0.0.0/16.

2. Allocate Subnets

Define a GatewaySubnet at 10.0.255.0/27 and AzureFirewallSubnet at 10.0.254.0/26.

3. Associate NSGs

Associate Network Security Groups (NSGs) to custom application subnets to filter traffic flow.