Windows Server: versions, editions, licensing

When wondering which version of Windows Server to choose for their business, users, as a rule, are faced with a wide variety, and it is far from always clear how to choose the most suitable option. The Windows Server operating system has not only different versions but also different editions. Let’s look at the differences between them.

What is a version of Windows Server?

In the 90s, during the time of Windows NT, each version of Windows Server had a unique number. For example, Windows NT had numbers 3.1, 3.51, and 4.0. But starting in 2000, Microsoft began to add, after the name, the year the operating system was launched: Microsoft Windows 2000, Windows Server 2003, 2008 (which also had version R2), 2012 (also with R2), 2016 and 2019, etc.

Each new version of Microsoft Windows Server introduces new functionality. For example, Hyper-V, Server Core, and BitLocker virtualization were introduced in Windows Server 2008, Windows and Nano Server containers were introduced in  Windows Server 2016, and  Windows Server 2019  brought Windows Admin Center — a new way to remotely administer the server infrastructure, improve the hyper-converged infrastructure and deep support for the Linux subsystem.

What is the end of support?

As they say, nothing lasts forever. And at some point, Microsoft stops releasing patches for legacy software. The date by which Microsoft releases product updates is called the end date of support. And after this date has passed, an outdated version of the OS will become an easy target for malware, since it will no longer receive security updates and, therefore, will be vulnerable to new exploits.

Microsoft operating systems are usually supported for at least 10 years. For example, the popular Windows Server 2003, released in April 2003, had extensive support that ended in 2015. Extended support for Windows Server 2008 R2 should end in January 2020, and Windows Server 2012 R2 will continue to receive updates until at least October 2023. Versions of Server 2016 and 2019 will receive updates through 2027 and 2029, respectively. Therefore, for security reasons, organizations should only use the latest versions of Windows Server.

What is the Windows Server edition?

When you buy a car, at least several sets of the same model are available to you. For example, the basic economical option, a luxurious option with leather seats and a sunroof, as well as a sporty option with larger wheels and a more powerful engine. In other words, each version of the car has its price and feature set for groups of customers with different budgets and needs.

The same goes for Windows Server editions. Each option includes functionality that is suitable for different companies, depending on their size and budget. For example, different editions may support a different number of users.

Differences between editions of Windows Server 2012 R2

To help understand some of the differences between OS editions, let’s look at an example of Windows Server 2012 R2:

The differences between editions of Windows Server 2016 and 2019

Virtualization Rights
You are allowed to run one physical Essentials instance as a Hyper-V host that hosts one Essentials virtual instance. You need to remove all roles except the Hyper-V role from the physical instance of Essentials to ensure compliance. Essentials are also suitable for one virtual instance on any other hypervisor.

Licensing model
based on the processor. Client licenses are not required, but you are limited to 25 users and 50 devices connecting to the server.

Hardware limitations
Essentials are limited to 64 GB of RAM and 2 CPUs on the computer on which it is installed.

Virtualization Rights
You can run up to two Hyper-V virtual machines or containers or one physical instance with a standard license. If you use the Hyper-V role only on a physical instance, you can use it as a Hyper-V host, and then host two Hyper-V virtual machines on that host. If you want to use multiple roles on a physical instance, you cannot start the virtual machine on top with the same license.

Licensing model
based on the core. Client licenses are required for each user or device that connects indirectly or directly to the server. For example, if you use the server as a file server, you will need a CAL for each user account or computer that accesses this file server on the network.

Hardware limitations
The standard is limited to a maximum of 24 TB of RAM and 512 cores.

Virtualization Rights
The unlimited number of virtual machines or Hyper-V containers. As stated above, you will buy licenses depending on how many cores you have on the hosts. At this point, you can run as many virtual machines as you like on the hosts using any role.

Licensing model
based on cores. Make sure that you do not accidentally select this release when installing on a physical server that does not host virtual machines. Client licenses are required for each user or device that connects indirectly or directly to servers in your environment.

Differences in licensing for Windows Server 2016 and newer

Although the prices for Windows Server 2012 R2, 2016, 2019 are the same, if you are using a standard license or a Datacenter license for Windows Server 2016 or later, there are some key changes that you need to be aware of. First of all, while Windows Server licenses have historically been sold for each processor/socket, in Windows Server 2016, the licensing model switched to each core.

Thus, if you have a server containing 2 processors with 24 cores, in Windows Server 2012 you will only need to buy one Standard or Datacenter license. In Windows Server 2016, you will have to buy licenses for all 24 cores. This becomes quite difficult, as there are many rules, but the main thing is that if you have a 16-core server, the costs will be approximately the same. However, OS licensing may be more expensive on servers with a higher core density.

Despite the change to the core license, the virtualization rules remain the same in Windows Server 2016 and later. Once you have licensed all your cores on the server, with the standard version you get 2 licenses for the Windows Server guest OS compared to the unlimited number in the Datacenter version.

Also, the features in Windows Server 2012 Standard and Datacenter were the same. But some features of Windows Server 2016, such as Storage Spaces Direct or shielded virtual machines, are only available in the Datacenter release.

Comparing installation options for Windows Server 2016 and 2019

Standard and Datacenter editions offer a variety of installation options. These options affect what features will be available after installation, such as a graphical user interface and a set of services. The following installation options are available:

Desktop Experience is an installation option that most people are familiar with. This option installs most of the functions and roles out of the box, including the desktop GUI. You will receive the Server Manager, which allows you to add and remove roles and components. The advantage is that the system can be easier to manage for people who are used to using a graphical interface. The downside is that you have more updates, reboots, and open ports to deal with.

Learn more from Microsoft here.

The Server Core lacks a graphical interface and several roles that are installed by default under the Desktop Experience option. The server core has less disk space and, therefore, a smaller attack area due to the smaller codebase. There are also fewer updates, reboots, and open ports to work with. This is a great option for infrastructure servers such as Active Directory domain controllers and DNS servers.

This edition lacks accessibility tools, built-in server configuration tools, and sound support. This version is no frills. It will not be amiss to make sure that you are familiar with command-line administration.

You can read more about this on Microsoft’s site.


Starting with Windows Server 2019, Nano is only available as a containerized image of the operating system. It is designed to run as a container inside a container host, such as the Server Core mentioned above. If you rely on container applications designed for server OS, then you will use this version to compile these applications.

Nano can be deployed using Standard or Datacenter versions, but you must have Software Assurance attached to the host server licensing. You can learn more about this on the website of Microsoft.