I have an environment with a Server 2008 R2 server that is my KMS Host.  It activates Windows 7, Server 2008 R2 and Server 2012 R2 clients.  I received a KMS key for Windows 10, but I'm not sure about adding it.  Will adding this key break the existing server?  Can I put the Windows 10 key on a Server 2008 host, and also, the network is disconnected, so how do I activate the key?

Hi Jeff,

I'm afraid Server 2008 R2 could not be a KMS host for Windows 10.

Here is the detailed reference:
Volume Activation (KMS, MAK, ADBA, AVMA):
http://social.technet.microsoft.com/wiki/contents/articles/22510.volume-activation-kms-mak-adba-avma.aspx

Adding a kms key would not break the existing server.

Best Regards,

Leo

Hi Leo - OK, so I already have a 2008R2 box that is the KMS host for 2008 and 2012.  Now I have a KMS host key for Windows 10.  I built a new 2012 box as the new KMS host.  How do I install the KMS host key for Windows 10 on it?  I ran the volume license tool and it says the kms host key is invalid?

Hi Jeff,

Have you installed the update?
Update that enables Windows 8.1 and Windows 8 KMS hosts to activate Windows 10:
https://support.microsoft.com/en-us/kb/3058168

Besides, about the problem of license, we could ask Activation Center for help:
https://www.microsoft.com/en-us/Licensing/existing-customer/activation-centers.aspx

Best Regards,

Leo