Regarding Client Access License (CAL)

[mhnahid]

Hi,

I want to know details about Client Access License or CAL,

My current system infrastructure as like => 4 Servers . #1 is DC, #2 is MAIL Server (IBM Lotus Domino) #3 is used for run some application and share Files and Folders and run SQL 2005 also, #4 used for run other application.

All servers are running with windows server 2003 r2 and last 3 servers are member of DC. Now I want to replace all of servers and upgrade all server OS to Windows Server 2008 R2 Standard . I've almost 300 user of my network and all are the member of DC.

So in this case , How many CAL I need to purchases with each windows and why ?

Can anyone please clarify about CAL in my situation. Thanks. !