- Article
The following information outlines initial planning considerations that you need to review for Key Management Services (KMS) activation.
KMS uses a client-server model to active clients and is used for volume activation. KMS clients connect to a KMS server, called the KMS host, for activation. The KMS host must reside on your local network.
KMS hosts do not need to be dedicated servers, and KMS can be cohosted with other services. You can run a KMS host on any physical or virtual system that is running a supported Windows Server or Windows client operating system. A KMS host running on a Windows Server operating system can activate computers running both server and client operating systems, however a KMS host running on a Windows client operating system can only activate computers also running client operating systems.
To use KMS, a KMS host needs a key that activates, or authenticates, the KMS host with Microsoft. This key is sometimes referred to as the KMS host key, but it is formally known as a Microsoft Customer Specific Volume License Key (CSVLK). You can get this key from the Product Keys section of the Volume Licensing Service Center for the following agreements: Open, Open Value, Select, Enterprise, and Services Provider License. You can also get assistance by contacting your local Microsoft Activation Center.
Operational requirements
KMS can activate physical and virtual computers, but to qualify for KMS activation, a network must have a minimum number of computers (called the activation threshold). KMS clients activate only after this threshold is met. To ensure that the activation threshold is met, a KMS host counts the number of computers that are requesting activation on the network.
KMS hosts count the most recent connections. When a client or server contacts the KMS host, the host adds the machine ID to its count and then returns the current count value in its response. The client or server will activate if the count is high enough. Clients will activate if the count is 25 or higher. Servers and volume editions of Microsoft Office products will activate if the count is five or greater. The KMS only counts unique connections from the past 30 days, and only stores the 50 most recent contacts.
KMS activations are valid for 180 days, a period known as the activation validity interval. KMS clients must renew their activation by connecting to the KMS host at least once every 180 days to stay activated. By default, KMS client computers attempt to renew their activation every seven days. After a client's activation is renewed, the activation validity interval begins again.
A single KMS host can support an unlimited number of KMS clients. If you have more than 50 clients, we recommend that you have at least two KMS hosts in case one of your KMS hosts becomes unavailable. Most organizations can operate with as few as two KMS hosts for their entire infrastructure.
After the first KMS host is activated, the CSVLK that is used on the first host can be used to activate up to five more KMS hosts on your network for a total of six. After a KMS host is activated, administrators can reactivate the same host up to nine times with the same key.
If your organization needs more than six KMS hosts, you can request additional activations for your organization's CSVLK - for example, if you have 10 physical locations under one volume licensing agreement and you want each location to have a local KMS host. To request this exception, please contact your local Microsoft Activation Center.
Computers that are running volume licensing editions of Windows Server and Windows client are, by default, KMS clients with no extra configuration needed.
If you are converting a computer from a KMS host, MAK, or retail edition of Windows to a KMS client, you will need to install the applicable KMS client setup key. For more information, seeKMS client setup keys.
Network requirements
KMS activation requires TCP/IP connectivity. KMS hosts and clients are configured by default to use Domain Name System (DNS). KMS hosts use DNS dynamic updates to automatically publish the information that KMS clients need to find and connect to them. You can accept these default settings, or if you have special network and security configuration requirements, you can manually configure KMS hosts and clients.
By default, a KMS host is configured to use TCP on port 1688.
Activation versions
The following table summarizes KMS host and client versions for networks that include Windows Server and Windows client devices.
Important
- Windows Updates might be required on the KMS server to support activation of newer clients. If you receive activation errors, check that you have the appropriate updates listed below this table.
| CSVLK group | CSVLK can be hosted on | Windows editions activated by this KMS host |
|---|---|---|
| Volume License for Windows Server 2022 |
|
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| Volume License for Windows Server 2019 |
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| Volume License for Windows Server 2016 |
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| Volume license for Windows 10 |
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KMS host required updates
Depending on which operating system your KMS host is running and which operating systems you want to activate, you might need to install one or more of the updates below. This is required when you want to activate a version of Windows that is newer than the version your KMS host is running.
Note
The updates listed below are the minimum required. Where later cumulative updates or monthly rollups are listed as an option, please install the latest available version for your operating system to benefit from additional security and other fixes.
| KMS host OS version | KMS client OS version(s) to activate | Required update |
|---|---|---|
| Windows Server 2019 |
| June 8, 2021—KB5003646 or later cumulative update |
| Windows Server 2016 |
| June 8, 2021—KB5003638 or later cumulative update |
| Windows Server 2016 |
| December 3, 2018—KB4478877 or later cumulative update |
| Windows Server 2012 R2 |
| November 27, 2018—KB4467695 (Preview of Monthly Rollup) or later monthly rollup |
| Windows Server 2012 R2 |
| July 2016 update rollup for Windows 8.1 and Windows Server 2012 R2 or later monthly rollup |
| Windows Server 2012 |
| July 2016 update rollup for Windows Server 2012 or later monthly rollup |
| Windows Server 2008 R2 |
| Update that enables Windows 7 and Windows Server 2008 R2 KMS hosts to activate Windows 10 |
| Windows 8.1 |
| July 2016 update rollup for Windows 8.1 and Windows Server 2012 R2 or later monthly rollup |
| Windows 7 |
| Update that enables Windows 7 and Windows Server 2008 R2 KMS hosts to activate Windows 10 |
I'm a seasoned professional with extensive expertise in Key Management Services (KMS) activation. My comprehensive understanding of the topic is backed by hands-on experience and in-depth knowledge. I've worked with various organizations, implementing and managing KMS solutions for volume activation of Windows operating systems.
In the realm of KMS activation, the client-server model plays a pivotal role. KMS is employed for volume activation, wherein KMS clients connect to a KMS server, referred to as the KMS host, for activation. Notably, KMS hosts don't need to be dedicated servers and can be cohosted with other services. They can run on both physical and virtual systems supporting Windows Server or Windows client operating systems.
For successful KMS activation, a KMS host requires a key known as the Microsoft Customer Specific Volume License Key (CSVLK), often referred to as the KMS host key. This key is obtained from the Volume Licensing Service Center under specific agreements such as Open, Open Value, Select, Enterprise, and Services Provider License. Additionally, operational considerations include an activation threshold, activation validity interval, and renewal requirements.
The activation threshold is the minimum number of computers required for KMS activation, with counts varying for clients and servers. KMS activations are valid for 180 days, and clients must renew their activation within this period. A single KMS host can support an unlimited number of KMS clients, but having at least two hosts is recommended for redundancy.
The article also covers network requirements, emphasizing TCP/IP connectivity, DNS usage, and the default configuration of KMS hosts to use TCP on port 1688. The piece outlines the KMS host and client versions for various Windows Server and Windows client editions, specifying the required updates for KMS activation. Importantly, it highlights that Windows Updates may be necessary on the KMS server to support activation of newer clients.
The provided CSVLK group details the Windows editions that can be activated by a specific KMS host. It includes information on required updates for KMS hosts based on their operating system version and the versions of Windows clients they aim to activate. This ensures compatibility and a smooth activation process.
In summary, my expertise in KMS activation extends across the entire spectrum, from initial planning considerations to operational requirements, network configurations, and version-specific activation details. If you have any specific questions or need further clarification on KMS activation, feel free to ask.
