Optimize Windows Autopilot bandwidth use with Connected Cache

As organizations move from on-premises device management to cloud device management, the efficiency of internet bandwidth management and software deployment becomes increasingly important. Windows Autopilot is used to simplify the deployment and management of new devices within an organization. However, IT admins face the challenges of internet bandwidth usage and increased time to download content from the internet when provisioning new devices using Autopilot. This is especially true when internet bandwidth is limited or where device provisioning is performed in bulk, which means the same content may be downloaded repeatedly.

In October 2024, we released Microsoft Connected Cache for Enterprise and Education in preview. This software-only caching solution delivers Microsoft content within enterprise and education networks. Connected Cache can be managed from the Azure portal or through the Azure Command-Line Interface (CLI). It can be deployed to as many Windows devices, Linux devices, or virtual machines (VMs) as needed. Managed Windows devices can be configured to download cloud content from a Connected Cache server by applying the client policy using management tools such as Microsoft Intune. To learn more, start with the overview of Microsoft Connected Cache for Enterprise and Education.

When combined, Autopilot and Connected Cache offer a comprehensive solution for efficient device management and content delivery. Autopilot streamlines the deployment and configuration of new devices, and Connected Cache ensures that updates and software installations are delivered efficiently.

We’ve heard from IT admins that they have cut their device provisioning time and saved significant internet bandwidth using Connected Cache with Autopilot for device provisioning.

Using Connected Cache in Autopilot device provisioning scenarios

Connected Cache is intended to serve as an on-premises content delivery network (CDN)—an alternative download source for cloud (internet download) content. Regardless of which Autopilot scenario your devices are provisioned under, if there is cloud content to be downloaded, Connected Cache will be used. See Windows Autopilot scenarios and capabilities for the complete list of scenarios including user-driven, pre-provisioning, existing devices, and more.

Connected Cache configuration basics

Your organization can configure devices for efficient downloads using the Windows Delivery Optimization settings in Microsoft Intune. There are two ways that Delivery Optimization can be configured to download content from a Connected Cache server:

• Using the Cache server hostname setting OR
• Using the Cache server hostname source setting

Configure Delivery Optimization for Windows | Using Connected Cache includes great guidance on which Delivery Optimization client settings will help ensure the best success in using Connected Cache.

The Cache server hostname setting allows you to statically configure the Connected Cache server for your Windows client(s). The Cache server hostname source setting allows you to configure your Windows client(s) to discover Connected Cache servers dynamically using Dynamic Host Configuration Protocol (DHCP). To learn more about DHCP, refer to this Dynamic Host Configuration Protocol article.

Connected Cache configuration – Cache server hostname source

As part of the DHCP discovery process, the Windows client doesn’t only get an IP address. The DHCP server also passes along other option information. Delivery Optimization can use this DHCP option mechanism to obtain and set the cache server information for downloads.

Using Cache server hostname source to specify how your clients can discover Connected Cache nodes is actually a two-part configuration:

• Configure the DHCP server with custom option 235 AND
• Configure the Delivery Optimization client Cache server hostname source setting

If you’ve never configured a custom DHCP option, you can find instructions in your respective DHCP server documentation (DHCP scopes in Windows Server) and refer to the screenshot from a Windows Server DHCP custom option configuration below. A few items to note:

• Most important is to specify the custom DHCP option on your DHCP server as text type. Not doing so has posed a challenge to some IT admins.
• The example shows an IP address, but a fully qualified domain name (FQDN) can be used as well.
• The value of the custom option is string. More than one value can be specified in a comma separated list.

DHCP custom option configuration example on Windows Server

Now that you have the DHCP custom option set, you will need to configure the Windows clients to look for this custom option. There are two options for setting the Cache server hostname source:

• 1 = DHCP Option 235 – which allows the Cache server hostname setting to take precedence, if both are set.
• 2 = DHCP Option 235 Force – which will, as the name implies, force use of the DHCP value for the Connected Cache server regardless of Cache server hostname setting.

Your clients are now ready to download content from a cache server that is dynamically set.

Pre-provisioning IT service scenarios configuration

What if you provision devices in bulk for your organization or provide IT services for another organization by pre-provisioning devices at a “second touch” facility? The table below provides some guidance on which Delivery Optimization Cache server client settings should be used in Autopilot scenarios.

There’s an important consideration specific to the outsourced IT/OEM pre-provisioning scenario. The end-user Intune settings for Connected Cache will be different than the provisioning IT/OEM, which poses some challenges.

Challenge 1: How do I set the Cache server hostname?

For IT/OEM offering bulk provisioning for other users as part of a PXE deployment, set the Cache server hostname source using a registry key. For example:

"HKLM\SOFTWARE\Policies\Microsoft\Windows\DeliveryOptimization" /f /v DOCacheHostSource /t REG_DWORD /d 2

Please note: This value will be retained after provisioning has completed, unless the user overrides this setting with their own Intune-configured Cache server hostname source setting.

Challenge 2: What if the user configures their own Cache server hostname settings?

There is no impact to the end user receiving the IT/OEM provisioned PC. Additionally, when the PC connects to the internet, there will be a nearly immediate update of the policy settings from the Intune service. See the table below for details.

Troubleshooting

What happens when you configure your DHCP server and Delivery Optimization, but devices are not pulling from the Microsoft Connected Cache server? Consider the basic troubleshooting steps below.  

Give the Windows device time to get the new DHCP option

You’ve spent time reading the documentation, configuring DHCP, setting Delivery Optimization settings, and you trigger a download of an Intune application, all in the period of 20 minutes, and it’s not working. Be patient—sometimes the DHCP options take time to propagate to the device, and most importantly, Delivery Optimization doesn’t query the DHCP option store on the device until a download is started. From talking with IT admins, we’ve found it to be the case that DHCP option configuration on Windows devices isn’t instantaneous.

Try another reboot. You can even run the following commands from PowerShell to trigger the device to get the DHCP options:

• ipconfig /release
• ipconfig /renew

After these commands have been run, acquire a Microsoft Store or Intune Company Portal application to trigger a Delivery Optimization download.

Ensure the DHCP server is returning the expected text in Option 235 for a device on your network

You can use PowerShell to query option values from the DHCP server using the Get-DhcpServerv4OptionValue. Note: This must be run on the DHCP server.

Ensure the Delivery Optimization Cache server hostname source setting has been configured on the Windows device

The steps below detail how you can get a Delivery Optimization log from the Windows device that will include information on the Cache server hostname source value and source of the value.

From PowerShell:

1. Enable-DeliveryOptimizationVerboseLogs -Force
2. Power off the Windows device, and power on the Windows device, or try the ipconfig steps described above
3. Acquire a Microsoft Store or Intune Company Portal application to trigger a Delivery Optimization download
4. Get-DeliveryOptimizationLog -Flush | Set-Content C:\dosvc.log
5. Disable-DeliveryOptimizationVerboseLogs -Force

If verbose logging is enabled and everything is working, the log you generated should include DOCacheHostSource = 1. The 7 refers to the way the setting was applied, via policy. There are two settings for DOCacheHostSource 1 or 2– this example shows 1.

If the DOCacheHost value is not present (and logging is verbose) then there was a problem retrieving DHCP option 235 or the value wasn’t present. For example, optionId = 235; szOption = (hr:80070490)–HR 80070490 is a common Windows error that translates to “not found.”  

If the DOCacheHost value is present, but the logs show the device is getting content from the CDN, then you should investigate whether the cache node is delivering content.

• Try the steps documented at Verify Microsoft Connected Cache for Enterprise and Education cache node functionality
• DeliveryOptimizationTroubleshooter.ps1 is also a good option for debugging content delivery issues

Note: We are continually improving/changing our logging, and the Delivery Optimization Troubleshooter will be the best source of this information in the future.

Next steps

The integration of Connected Cache with Autopilot provides efficient internet bandwidth management and software deployment. Used together, these tools offer a powerful solution for enterprise organizations.

For more about Connected Cache, don’t miss the Technical Takeoff session Deploying Microsoft Connected Cache for Enterprise at scale—streaming live on Wednesday, March 5, at 11 AM PST and available on demand immediately after airing.

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