Q: What is a CAL (Client Access License)?

This is a type of commercial software license. It is not a software product itself. A CAL is needed for each user or device that connects to the server to use its services, which include file sharing, printing, or authenticating against a domain controller. It is a license that allows a user or device to legally access server software services. Microsoft uses this model for their server products, such as Windows Server, Exchange Server, and SQL Server.

Q: What is an RDS CAL?

An RDS CAL (Remote Desktop Services Client Access License) is a license that allows users or devices to connect to and use a Windows Server with the Remote Desktop Services (RDS) role installed. This license gives the user or device the legal right to access the server's published resources, including virtual desktops and applications, through the Remote Desktop Protocol (RDP).

Q: What are the types of RDS CALs?

There are two types of RDS CALs: Per-User RDS CAL and Per-Device RDS CAL. The correct selection of one is determined by the way the users and devices of your organization connect to the server.

Q: What is a Per-User RDS CAL?

A Per-User RDS CAL is a license assigned to a specific user. It allows that user to connect to a Remote Desktop Services server from any number of devices. Companies with more devices than users find this model cost-effective. Users in an Active Directory (AD) domain environment can use Per-User CALs since they are assigned to a user in Active Directory.

Q: What is a Per-Device RDS CAL?

A Per-Device RDS CAL is a license assigned to a specific device. It allows any user who uses that device to connect to a Remote Desktop Services (RDS) server. This licensing model works well in environments like factories, call centers, hospitals, libraries, hotel kiosks, or school computer labs where multiple users share the same device.

Q: Can Per-Device RDS CALs be tracked from Licensing Manager?

Per-Device RDS CALs can be tracked from Licensing Manager. Per-User RDS CALs can be tracked only in the Active Directory environment, they cannot be tracked in a workgroup environment.

Q: Can I revoke RDS CALs?

Per-Device lets you revoke up to 20% of RDS CALs. This is not possible with Per-User.

Q: What are Temporary RDS CALs?

Temporary RDS CALs are part of the Per-Device RDS CAL licensing model. They are not a separate product to buy. Instead, they are temporary licenses issued by a Remote Desktop Licensing server. When a new device connects to an RD Session Host server in Per-Device licensing mode for the first time, the server checks with the RD Licensing server and provides a temporary RDS CAL to that device.

Question 1

What is a CAL?

Accepted Answer

A CAL (Client Access License) is a commercial software license, not a software product itself. It provides the legal right for a user or device to connect to the server.

You need a CAL for any user or device accessing services such as:

File sharing & printing
Active Directory authentication
Remote Desktop Services (RDS)

Question 2

What is a RDS CAL?

Accepted Answer

A RDS CAL (Remote Desktop Services Client Access License) is a license that allows users or devices to connect to and use a Windows Server with the Remote Desktop Services (RDS) role installed. This license gives the user or device the legal right to access the server's published resources, including virtual desktops and applications, through the Remote Desktop Protocol (RDP).

Question 3

What is the difference between a "Windows Server CAL" and an "RDS CAL"? Important

Accepted Answer

This is a common point of confusion. You typically need both:

Windows Server CAL: Lets a user/device access the server network (File, Print, DNS).
RDS CAL: Specifically required when a user/device initiates a Remote Desktop session to interact with the graphical interface or run applications remotely.

If you are using Remote Desktop Services, you technically need an RDS CAL for each user or device.

Question 4

Do I need an RDS CAL for the Administrator account?

Accepted Answer

No. Windows Server includes two concurrent administrative remote desktop connections built-in.

These are strictly for server administration and maintenance. If you are using these sessions to run business applications (like Office or an ERP), you are violating the license agreement and require purchased RDS CALs.

Question 5

Can I use newer RDS CALs on an older Windows Server? Downgrade Rights

Accepted Answer

Yes. RDS CALs are backward compatible.

For example, if you purchase a Windows Server 2022 RDS CAL, you can install it on a license server to authorize connections to a Windows Server 2019 or 2016 Session Host.

Note: The reverse is NOT true. You cannot use 2016 CALs to access a 2022 Server.

Question 6

Can I use RDS CALs in a Workgroup (No Domain)?

Accepted Answer

Yes, but with limitations. In a Workgroup environment (where there is no Domain Controller), you generally must use Per-Device RDS CALs.

Per-User CALs are designed to track Active Directory accounts. While technically possible to install Per-User CALs in a Workgroup, the tracking and reporting features will not function correctly, and compliance is difficult to prove.

Question 7

What are "Temporary" RDS CALs?

Accepted Answer

Temporary CALs are a feature of the Per-Device licensing model.

When a new device connects for the first time, the license server issues a temporary 90-day token.
This allows immediate access even if you haven't bought permanent licenses yet.
Upon the second connection, the server attempts to upgrade the Temporary CAL to a Permanent CAL.

Question 8

Can RDS CALs be revoked or transferred?

Accepted Answer

Per-Device: Yes, you can manually revoke up to 20% of your issued CALs using the Licensing Manager console. This allows you to reclaim a license from a broken or lost computer immediately.
Per-User: No. User CALs are not strictly "assigned" in the same way; they simply return to the available pool when not in use. You cannot manually revoke them.

Question 9

Who should choose Per-User RDS CALs?

Accepted Answer

A Per-User CAL is linked to a specific person (Active Directory account). That person can access the server from unlimited devices.

Choose this if:

You have employees who work remotely or travel often.
Your staff uses multiple devices (Laptop + Phone + Home PC).
You have more devices than employees (e.g., 50 users, 100 devices).
Your servers are joined to an Active Directory Domain.

Question 10

Who should choose Per-Device RDS CALs?

Accepted Answer

A Per-Device CAL is linked to a specific physical computer. Unlimited users can share that one device to connect to the server.

Choose this if:

You have shift workers (e.g., a 24-hour call center where 3 people share 1 desk).
You have public workstations (Classrooms, Labs, Hotel Kiosks).
You have a "Workgroup" environment (No Active Directory).

Frequently Asked Questions

Frequently Asked Questions

1. Core Concepts

2. User vs. Device Models

3. Compatibility & Management