IAS tracks the amount of time a user is logged on through the Network Access Server (NAS). When the NAS sends an accounting packet, IAS receives and stores the information. You can capture this information in the IAS accounting log. This log file captures the user’s name, the start times, end times, the time at which the user logged in and logged out for the session, and other session information. The start- and end-dates and times can be sorted and converted to elapsed time for conversion to a billing value if desired.
IAS is a RADIUS server, and uses user data stored in a Windows NT Domain Controller to verify authentication requests received via the RADIUS protocol.