In addition to the license that is required to install and run Windows Server and the license that is required to install
and run an operating system on each client computer, you also need a Client Access License (CAL) for each client connection to
Windows offers two types of CAL licensing modes:
Per Server. Per Seat
You can switch from Per Server to Per Seat licensing one time without any cost, but you cannot swtich from Per Seat to Per
Server. Thus, if you are unsure which licensing method is best, it is safest to select Per Server initially.
Per Seat licensing
Having a valid Per Seat mode CAL
guarantees access only to a server configured in the Per Seat mode.
It does not guarantee access to a server that is licensed in the Per Server mode. Such a connection also consumes one of the
licenses assigned to the pool of available Per Server licenses assigned to the server. Therefore, the client can connect only
if there are fewer connections than the limit allowed on the server.
Per Seat example
The Per Seat option is often the most economical one for networks in which clients tend to connect to more than one server
For example, suppose that you have several servers that users must connect to during the day. On one server you have Microsoft
SQL Server installed, on another server you have Microsoft Exchange 2000 installed, and on a third server you have Microsoft
SNA Server installed. Users often access these servers simultaneously.
If you used Per Server licensing, you would have to buy one license for each user for each server. If you had three users, you
would have to buy three licenses for each server for a total of nine licenses. With Per Seat licensing, you would need to buy
only one license Per Seat license for each user, or a total of three licenses. Now you can see why Per Seat licensing is much
more cost effective when users need to access multiple servers in the organization.
Per Server licensing
With Per Server licensing, you must have at least as many CALs dedicated to a server product as the maximum number of client
computers that will connect to that product concurrently. For example, if you are logged on to a workstation and you connect to
\\server\apps and \\server\public from that workstation, that constitutes a single connection and uses only one CAL. However,
if you log on to two different workstations using the same username and connect to the server from both, that is considered two
connections and uses two Per Server CALs.
If a network has multiple servers, each server licensed in Per Server mode must have at least as many CALs dedicated to it as
the maximum number of clients that will connect to it at any one time.
After the limit is reached on a server, it does not allow additional connections. Clients attempting to connect to the server
receive an error message. Connections made by administrators are counted in the total number of concurrent connections, but
after the limit is reached, administrators are still allowed to connect. This permits them to manage a lockout situation. Other
users can connect only after enough clients (including administrators) have disconnected to get below the limit.
Per Server example
The Per Server licensing mode is primarily for when a network has only one server. Per Server may be the most economical
licensing mode for servers used only occasionally. If you are a small company, you could install Microsoft SQL Server,
Microsoft Exchange Server, and Microsoft SNA Server on a single Windows Server machine.
Because single users would be connecting only to this machine, you could buy Per Server based on the number of simultaneous
connections you anticipate on this machine.
If you have 50 users and anticipate that 35 will be attempting to connect to the machine simultaneously, then you would buy 35
Per Server licenses.
Suppose yours is a large company with many users who connect to three different servers concurrently.
Why would Per Seat licensing, potentially, be more economical than Per Server.
With Per Seat licensing, each workstation can connect to as many servers as necessary.
With Per Server licensing, each server must have as many licenses as there are client connections.
Thus in the above scenario, you would need only one CAL for each workstation using Per Seat licensing.
With Per Server licensing, you would need three CALs per workstation.
If your company uses Microsoft(r) BackOffice products, you must have licenses for these products in addition to the licenses
required to connect to the Windows Server itself. For more information regarding licensing, see the Microsoft Web site.
In the next lesson, domain or workgroup membership decision making will be discussed.