Microsoft Windows and Office License for Diskless
Microsoft License for Client:
Microsoft License includes RTL (Retail License), OEM (Original Equipment Manufacturer License, for example, the free Windows license which is given for purchasing DELL and HP computers) and VOL (Volume License). For VOL, it can be divided into MAK (Multiple Active Key) and KMS (Key Management Service).
Microsoft License for Server:
CAL is a concept for server (Client Access License), and it stands for the number of clients that is allowed to connect to the server.
Take Windows 2008 Server for example. It is free for five clients in the beginning, if you want it connect more clients, you need to buy a CAL. And CAL is divided into device-based CAL (Device CAL) and user-based CAL (User CAL).
How to Choose Microsoft License for Diskless:
The license mode of Windows and Office which is suitable for diskless is KMS (Key Management Service) Volume License. This mode is completed by establishing the KMS host service on the LAN. KMS host needs to connect Microsoft to activate Windows license, while KMS clients does not have to connect to Microsoft. In this way, we have to deploy KMS host and configure DNS. The KMS clients which need to be activated should exceed a certain amount (For Windows 7, it needs at least 25 real machines or virtual machines), and it also needs to be updated and activated again within 180 days, otherwise, it will be expired.
Windows License Requirements
Q: We installed CCBoot on Windows Server 2008 R2. Do we need CAL for all clients?
A: Yes, you need CAL for all clients when CCBoot is installed on server.
Q: Do we need RDS license too?
A: Now, CAL is enough,so RDS license is not necessary since Remote services are not used to connect to server.
IMPORTANT: Although OEM license are cheap and easy to find, there is not set way to activate the OEM windows license in a diskless environment. Thus, we do not recommend purchasing OEM license if you are looking use genuine windows license.
Look for KMS volume license.