Adsizer.exe, the Active Directory Sizer, "lets you estimate the hardware required for deploying Active Directory based on your organization's profile, domain information, and site topology.
Based on user input and internal formulas, Sizer estimates the number of the following:
. Domain controllers per domain per site . Global Catalog servers per domain per site . CPUs per machine and type of CPU . Disks needed for Active Directory data storageIn addition, Sizer provides approximate estimates for the following:
. Amount of memory required . Network bandwidth utilization . Domain database size . Global catalog database size . Intersite replication bandwidth required"