CALs are required by Microsoft licensing for all users or devices that access Windows Server Standard or Windows Server Datacenter. When a customer buys Windows Server Standard or Datacenter, they receive a server license that allows them to install the operating system on one computer.

Do I need CALs for each server?

The general requirement is, any User or Device that accesses the server software, either directly or indirectly, requires a CAL. But you dont need purchase CAL for each user/computer adding to AD and you only need appropriate amout of CALs for your users or devices to use Active Directory legally.

Do I need a CAL when my Windows server is used to run a web server?

Generally speaking – server to server communication does not require a CAL. … If you use a Linux server to run a web server, but your users accessing the web server are being authenticated via Windows Server – users (or the devices they use) will need a Windows Server CAL.