12. What is Client Access License (CAL) works in Windows server products?

A CAL is a Client Access License. In the world of Microsoft licensing, for every server you use the users/devices utilizing that server have to be licensed as well. This is not a physical piece of software installed on the user’s machine, it is instead a grant to access the server. This can add to the complexity of managing them because there is typically no request from an end-user to load the software, nor is there a software asset inventory showing a CAL installed somewhere. It is instead typically up to IT to develop a correlation between users or devices and servers.

For example; if you're running Microsoft Windows server, each user or device requires a CAL. If you then add SharePoint on that server, you also then need a CAL for that. If you're running SQL server to support SharePoint, you need a CAL or a processor license for SQL. The list goes on and on...if you're using the resources of the server chances are there is a corresponding access license requirement.

CALs come in three basic forms: user, device or external connector.

User CALs (client access license based on user)

With the User CAL, you purchase a CAL for every user who accesses the server to use services such as file storage or printing, regardless of the number of devices they use for that access. Purchasing a User CAL might make more sense if your company employees need to have roaming access to the corporate network using multiple devices, or from unknown devices, or simply have more devices than users in your organization.

Device CALs (client access license based on device)

With a Device CAL, you purchase a CAL for every device that accesses your server, regardless of the number of users who use that device to access the server. Device CALs may make more economic and administrative sense if your company has workers who share devices, for example, on different work shifts.

External Connectors

If you want external users—such as business partners, external contractors, or customers—to be able to access your network, you have two licensing options:

1. Acquire CALs for each of your external users.

2. Acquire External Connector (EC) licenses for each server that will be accessed by your external users.

The general rule of thumb is that you license the “least”. So, if your devices outnumber your users, buy User CALs…if your users outnumber your devices buy Device CALs. If you have external users (vendors, clients, etc) that are authenticated by your server you either need to have a CAL for them or if they number significantly high or cannot be counted you would go with an External Connector license for that server.

External Connector licenses allow unlimited external access to a specific server. However; you cannot use an External Connector license to replace internal use CALs.