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KMS Activation Timing and Discovery for Volume Activation
- Article
- 08/31/2016
- 2 minutes to read
In this article
Applies To: Windows 10, Windows 8.1, Windows Server 2012 R2
On this page
KMS activation timing
KMS discovery search order
KMS activation timing
KMS activation timing is controlled by two settings: the Activation and Renewal timers:
The KMS Activation Interval determines how often the KMS client attempts activation before it is activated. This value is set on the client by running slmgr.vbs /sai . See the sections “Slmgr.vbs Options” and “Registry Settings” for more information. Once a system contacts a KMS host, the KMS host setting will override the local client setting.
The KMS Renewal Interval determines how often the KMS client attempts reactivation with KMS, once it has been activated. This value can be set using slmgr /sri interval. The interval is set in minutes. The default value is 10,080 minutes [7 days]. This value can be set on the client but will be overridden by the value that the KMS host provides.
In operation, the KMS client attempts to contact a KMS host on startup and again every Activation Interval minutes upon failure. By default, this happens every two hours. When KMS activation succeeds, the client receives and stores the KMS host’s Renewal Interval, and Windows activates for 180 days. Activation renewal operates as a sliding window, similar to a Dynamic Host Configuration Protocol [DHCP] lease. The client is activated for 180 days but still attempts reactivation every Renewal Interval minutes—by default, 7 days. If it succeeds, the 180-day period is reset. If it fails, the system will watch for network changes or other qualifying events to trigger another attempt. After 15 minutes, the system stops monitoring for qualifying events but still attempts every Activation Interval minutes.
KMS discovery search order
When KMS auto-discovery is enabled [default] and KMS host caching is not disabled, KMS clients will use the following order to determine which KMS to use [they will try each step until an activated KMS host with the correct key responds]:
SKU-specific value in the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform\AppID\SKUID\KeyManagementServiceName REG_SZ registry value
AppID-specific value in the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform\AppID\KeyManagementServiceName REG_SZ registry value
Global value in the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform\KeyManagementServiceName REG_SZ registry value
SKU-specific cached KMS host [This is the cached identity of the host used in the last successful KMS activation.]
DNS auto-discovery [weight and priority honored]
If a cached KMS does not respond, discovery is performed.
See also
Volume Activation Technical Reference
Volume Activation Overview
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Key Management Services [KMS] activation planning
- Article
- 12/23/2021
- 7 minutes to read
In this 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, see KMS 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.
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.
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 |
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