RDS CALs explained: why they are an addition and not a replacement
The most common licensing error in SMEs: RDS CALs do not replace regular ones; they are an addition. When RDS applies, when the administration exception applies, and why a license server is mandatory.
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Short answer: An RDS access license does not replace the normal access license; it is in addition to it. A workstation that operates on the server via Remote Desktop therefore needs two licenses: a Windows Server CAL and an RDS CAL. This is the most common licensing error in small and medium-sized businesses.
Why two licenses and not one
Microsoft separates two different rights. The normal CAL allows access to server services, i.e., file shares, directory services, print services. The RDS CAL additionally allows opening a graphical session on the server and working directly there.
Since a Remote Desktop session always uses server services, you need both rights. They are not mutually exclusive; they build on each other.
Since a Remote Desktop session always uses server services, you need both rights. They are not mutually exclusive; they build on each other.
When RDS applies at all
Not every remote connection is Remote Desktop in the licensing sense. You are affected in these cases:
- A terminal server on which several employees work simultaneously.
- Individual applications that are published from the server and displayed on the client.
- Virtual desktops running centrally on the server.
Administration is not affected. Windows Server allows two simultaneous connections exclusively for administrative purposes, without an RDS license. As soon as productive work is done on it, this exception ends.
It is precisely at this point that many companies unknowingly slip into under-licensing. The administrator sets up access "just for a moment," and half a year later, three people are working with it daily.
"Remote access was originally only intended for emergencies - a year later, three permanent home office workstations were connected to it, completely without an RDS CAL." An IT consultant describes a typical finding during a license audit, which had developed gradually without anyone consciously noticing it.
RDS is also available on a user and device basis
The same logic as for normal access licenses applies a second time here. The RDS User CAL belongs to a person, the RDS Device CAL to a device. And the decision rule is the same: count people, count devices, license the smaller number.
You don't have to choose the same type as for normal CALs, even if this usually coincides in practice.
How to calculate a Remote Desktop workstation
A company with eight people, all working on a terminal server via Remote Desktop, needs:
- a server license for the hardware,
- eight normal access licenses,
- eight RDS access licenses.
Anyone who only buys the server license and the eight RDS CALs is under-licensed, although the system runs perfectly. Windows Server does not check this.
The license server is mandatory
RDS CALs must be stored and activated on a Remote Desktop license server. Without this, the service runs in a test phase and then stops operating. Plan this step firmly, it is regularly forgotten and then leads to an outage that looks like a technical defect.
Calculate securely
The CAL configurator takes RDS into account and automatically adds the additional licenses as soon as you answer the question about Remote Desktop with Yes.
The licenses themselves can be found under Access Licenses. The article on User and Device CALs explains how normal CALs work, and the Server Guide provides all the basics.
