Operating System Updates and Delivery Optimization

This article will explain what Delivery Optimization and Bandwidth Control are and how to use them.

1. Description
2. Where can I find these options in the HEIMDAL Dashboard?
3. What are the Registry Keys the HEIMDAL Agent updates when these options are enabled?
4. What is Heimdal recommending for bandwidth limitation?

DESCRIPTION

Microsoft Delivery Optimization (DO) is a Windows component and cloud-managed peer-to-peer distribution service that helps devices download Windows updates, Microsoft Store apps, and other Microsoft content more efficiently.
Instead of every device downloading the same update separately from Microsoft’s servers, Delivery Optimization lets devices share already downloaded content with other devices on the same network (or, if allowed, over the Internet) - similar to a controlled P2P system managed by Windows.

How It Works

• DO creates a local cache of downloaded update files and can share those chunks with other Windows devices.

• It uses content hashing and Microsoft’s cloud service to ensure file integrity and trust.

• It works alongside Windows Update, Microsoft Store, Intune, and WSUS.

• You can control its behavior via Group Policy, Intune, or the registry, using settings like DownloadMode.

Bandwidth control refers to the practice of managing, allocating, or limiting the amount of network capacity (data transfer rate, measured in bits per second) that devices, applications, or services can use within a network. Its goal is to prevent congestion, prioritize critical traffic, and ensure fair and efficient use of available network resources - especially in environments where multiple systems share a limited Internet or WAN link.

WHERE CAN I FIND THESE OPTIONS IN THE HEIMDAL DASHBOARD?

The Delivery Optimization and Bandwidth Control option can be found under each Group Policy setting. To access them, please follow these steps:

1. Log in to your HEIMDAL Dashboard account.
2. Access the Endpoint Settings area and open the Group Policy settings that you want to apply.
3. Navigate to Patch & Assets -> Operating System Updates and scroll down to the bottom

IMPORTANT
When a new Group Policy is created, the Delivery Optimization option is automatically enabled. 

WHAT ARE THE REGISTRY KEYS THAT THE HEIMDAL AGENT UPDATES WHEN THESE OPTIONS ARE ENABLED?

The Registry Keys updated by the HEIMDAL Agent to control the Delivery Optimization are:

1. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Config - DODownloadMode 
   This defines how Delivery Optimization retrieves Windows or Microsoft Store updates. With the Delivery Optimization turned ON, the HEIMDAL Agent will set the value to 1, meaning “LAN (Local Network)” - Windows will download updates from Microsoft’s servers and other PCs on the same local network, but not from PCs on the Internet.
2. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Config - DownloadMode_BackCompat 
   This is a backward-compatibility flag for older Windows builds or mixed-version environments. It mirrors DODownloadMode legacy processes or GPO-based systems that reference the older naming convention. With the Delivery Optimization ON, Heimdal will set the value to 1, meaning he compatibility setting matches the current mode (LAN only).
3. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Settings - DownloadMode
   Same functional purpose as the first key, but placed under the Settings subkey that represents active, applied configuration rather than policy defaults. With the Delivery Optimization ON, Heimdal will set the value to 1, enforcing LAN-only optimization - downloads from Microsoft servers and local PCs only.

The Registry Keys updated by the HEIMDAL Agent to control the Bandwidth Control are:

1. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Config - DOMaxBackgroundDownloadBandwidth 
   Sets the maximum download bandwidth (in kilobits per second) for foreground DO activities. Foreground downloads = User-initiated or high-priority downloads, such as:
   - Windows updates are manually triggered by a user.
   - Microsoft Store app updates are initiated interactively.

2. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DeliveryOptimization\Config - DOMaxBackgroundDownloadBandwidth
   Example: If you enable the option Bandwidth Control in the Heimdal Dashboard, and you add the limit to be 10 Mb, the Heimdal agent will modify the two registries and add the value 10000 kilobits. 
   IMPORTANT
   When the OS Updates product is disabled, the HEIMDAL Agent will restore the registry keys to the previous settings. If Delivery Optimization is managed through an Active Directory GPO, the HEIMDAL Agent will not be able to set DODownloadMode to 1. 

WHAT IS HEIMDAL RECOMMENDING FOR BANDWIDTH LIMITATION?

Based on our internal testing, we recommend allocating bandwidth proportionally by dividing the total available bandwidth at a given site by the number of endpoints connected to it. Examples are listed below: