What is the difference between a Server license and a CAL? Why do I need both?
The Server license gives the license holder the right to install and use the server software. The CAL grants the right for a device or user to access the server software. This offers license affordability to organizations of all sizes.

When do I need to acquire a CAL?
A CAL is required when a user or device accesses or uses the server software. If access is through the Internet and is unauthenticated (as at a public website), a CAL is not required.

Are the five CALs that come with my purchase of Windows Server 2008 Standard edition per user or per device?
The five CALs that come with the purchase of Windows Server 2008 Standard may be designated for either user or device. Any additional CALs acquired afterward are bought as either user or device CALs.

Can I use a device CAL and a user CAL to access the same server?
Yes. Device and user CALs, as well as Remote Desktop Services device and user CALs, can be used to access the same server.

Is each CAL "tied" to a specific user or device?
Yes. CALs must be assigned to specific users or devices. If a user leaves the company or a device is retired, the CAL can be reassigned.

I have some extra CALs from an older version that are not being used. Can I apply these to servers running a newer version?
No. CALs must be the same version as—or a more recent version of—the server software they are accessing.

Do I need to upgrade my Server CALs for access to future releases of Windows Server?
Future releases of Microsoft Server software will require CALs of the same version for users or devices accessing the software. Either new CALs must be bought when the new version releases, or Software Assurance* must be maintained on the prior version's CALs, which gives the rights to the next version.

* Software Assurance may be purchased through Volume Licensing.