Assume you are at a client site and plan to deploy a Windows Server (2008 / 2008-R2) or Windows Clients (Windows Vista / Windows 7) and want to check if they do already have KMS Services running on their network.
It’s very simple. Just open a command prompt and type the following command:
nslookup -type=srv _vlmcs._tcp
If KMS Services are present on the network the results will be listed as shown in the picture below.
Upgrade your existing KMS Service to support Windows 7 and Windows 2008 R2
Volume Activation changes in Windows7
Fundamentals of Volume Activation