[Activation threshold]: #upgrade-and-migration 'Activation threshold Minimum of 25 workstation systems or five server systems as clients for KMS KMS hosts maintain a cache of the 50 most recent workstation requests, and KMS activations expire every 180 days (ref Activation validity interval). Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 36' [Activation validity interval]: #upgrade-and-migration 'Activation validity interval 180 days for KMS activations, although clients attempt to renew every 7 days Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 37' [Active Directory-based activation]: #upgrade-and-migration 'Active Directory-based activation Use of AD DS for communication and data storage instead of a KMS host Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 39' [AVMA]: #upgrade-and-migration 'Automatic Virtual Machine Activation (AVMA) Simplifies the process of activating VMs created on Hyper-V servers, whereby a binding is created between the host server and the activation mechanism on each VM, which are activated automatically and remain so. Requires Datacenter Edition of WS 2016 or WS 2012 R2 on the host server and a specific key, depending on the version of Windows Server on the VM. Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 41' [MAK Independent]: #upgrade-and-migration 'MAK Independent each computer using the MAK must perform an individual activation with Microsoft over the Internet or by telephone Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 36' [MAK Proxy]: #upgrade-and-migration 'MAK Proxy VMAT collects installation IDs from target computers, activates them all at once, then receives and deploys confirmation IDs from Microsoft back to targets Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 36' [MAK]: #upgrade-and-migration 'Multiple activation key (MAK) Product key that can be used to activate multiple Windows systems (suitable for small networks). Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 35' [VAMT]: #upgrade-and-migration 'Volume Activation Management Tool (VAMT) Collects installation IDs from target computers, sending them to Microsoft using a single connection and receiving confirmation IDs in return, which are deployed to targets. Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 35' [GVLK]: #upgrade-and-migration 'generic volume licensing key (GVLK) Can be used to configure KMS clients that are not KMS clients by default, like those with retail, MAK, or KMS host licenses Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 39' [KMS]: #upgrade-and-migration 'Key Management Service (KMS) Client/server application that enables client computers to activate their license doperating system products by communicating with a KMS host computer on the local network (suitable for large networks). Requires a minimum of 25 workstations (ref Activation threshold) and uses TCP port 1688. KMS hosts create an SRV resource record on DNS to identify it. Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 35' [Volume Activation Services]: #upgrade-and-migration 'Volume Activation Services Windows Server role that must be added before installing a KMS host Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 37' [Volume Activation Tools]: #upgrade-and-migration 'Volume Activation Tools Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 37' [Volume Licensing Services]: #upgrade-and-migration 'Volume Licensing Services Windows Server role that must be added before being able to use Active Directory-based activation Zacker, Craig. _Installation, Storage and Compute with Windows Server 2016: Exam Ref 70-740_. 2017: 40' Server installations are influenced by choice of activation model. [MAK][MAK] is suitable for small networks, but large enterprises may opt for [KMS][KMS]. - **MAK** activations are subdivided into [Independent][MAK Independent] and [Proxy][MAK Proxy], based on whether or not a [VAMT][VAMT] is used. - **KMS** activations, which distribute [GVLK][GVLK]s, are valid for a [period of time][Activation validity interval] and require the installation of a [role][Volume Activation Services] and [management tools][Volume Activation Tools]. KMS operates on TCP port 1688. - [**AVMA**][AVMA] simplifies the process of activating Hyper-V VMs running Windows Server 2012 or 2016. [**Active Directory-based activation**][Active Directory-based activation] is an alternative for enterprises who opt to activate licenses through the existing AD DS domain infrastructure. Any domain-joined computers running a supported OS with a GVLK will be activated automatically and transparently. The domain must be extended to the Windows Server 2012 R2 or higher schema level, and a **KMS host key** must be added using the VAMT. After Microsoft verifies the KMS host key, client computers are activated by receiving an activation object from the DC. [MS Docs](https://docs.microsoft.com/en-us/windows/deployment/volume-activation/activate-using-active-directory-based-activation-client)