Dive into the FRESH Updates of Azure Network Features!

Running out of IP addresses in your Microsoft Azure subnet used to mean downtime and a messy redesign. But with Azure’s new support for multiple address prefixes in subnets, that challenge is a thing of the past.

The Challenge with Traditional Subnets

Traditionally, when you created a subnet in Azure, you had to assign a single address prefix. That range determined the number of IP addresses available. For example:

• A /24 subnet gives you 251 usable IP addresses.
• A /27 subnet provides only 27 usable IP addresses.

If your deployment grew beyond that range, the only option was to build a new, larger subnet and migrate workloads—a time-consuming process that often introduced downtime and complexity.

Azure’s Multi-Prefix Solution

Now, Azure Cloud has introduced the ability to assign multiple address prefixes to a single subnet. This new feature changes the game for IT infrastructure and networking teams:

• Scalability: Easily expand your subnet without rebuilding or migrating services.
• No Downtime: Existing resources remain online while new prefixes take effect.
• Simplified Management: Manage fewer subnets for the same workload.

Once the first prefix runs out of addresses, Azure automatically starts assigning from the next prefix. It’s dynamic scaling built right into Azure Networking.

Key Considerations

While powerful, there are some details to keep in mind:

• As of now, adding prefixes can only be done with PowerShell, Azure CLI, or template deployments (though portal support may come soon).
• Network Security Groups (NSGs) and route tables apply across all prefixes in a subnet.
• You cannot remove a prefix if any IP addresses from that range are still in use.

This feature works with Virtual Machines (VMs) and VM Scale Sets, making it especially valuable for growing deployments.

Demo Walkthrough

See the video above for a full walkthrough. The code used in the video is linked below.

In practice, the process is straightforward:

1 Verify your Azure environment and module versions.

2. Use PowerShell to update your existing subnet configuration, adding both the original and new prefixes.

3. Apply the changes with Set-AzVirtualNetwork.

4. Confirm that your subnet now supports multiple prefixes.

Creating new VNets with multiple prefixes follows the same logic, allowing you to define flexible address spaces right from the start. And if you no longer need a prefix, you can safely remove it (as long as no IPs are in use).

Why This Matters for Cloud Networking

For organizations relying on Azure Cloud, this update streamlines networking and IT infrastructure management. No more scrambling to re-architect when subnets run out of IPs. Instead, teams gain the flexibility to scale on demand while keeping workloads online.

This is a welcome improvement for anyone designing Cloud Networking architectures in Azure—whether you’re managing enterprise IT infrastructure or optimizing workloads for growth.

Links:

A Beginner’s Guide to the AZ-900
https://www.udemy.com/course/beginners-guide-az-900/?referralCode=C74C266B74E837F86969

Zero to Hero with Azure Virtual Desktop
https://www.udemy.com/course/zero-to-hero-with-windows-virtual-desktop/?referralCode=B2FE49E6FCEE7A7EA8D4

Hybrid Identity with Windows AD and Azure AD
https://www.udemy.com/course/hybrid-identity-and-azure-active-directory/?referralCode=7F62C4C6FD05C73ACCC3

Windows 365 Enterprise and Intune Management
https://www.udemy.com/course/windows-365-enterprise-and-intune-management/?referralCode=4A1ED105341D0AA20D2E

Create multiple prefixes for a Subnet
https://learn.microsoft.com/en-us/azure/virtual-network/how-to-multiple-prefixes-subnet?WT.mc_id=AZ-MVP-5004159

PowerShell Commands
https://github.com/tsrob50/CiraltosTools