How can I ascertain which machine a user is currently using?

A. To identify which machine a particular user is using, you can run a series of commands (and even create a script to automate this process) by performing the following steps:

For example, to locate a user named Kevin, I performed the following series of commands and received the indicated responses:

   C:>nbtstat -R   Successful purge and preload of the NBT Remote Cache Name Table.   C:>net send kevin .   The message was successfully sent to KEVIN.   C:>nbtstat -c   Local Area Connection:   Node IpAddress: [200.200.200.5] Scope Id: []   NetBIOS Remote Cache Name Table   Name Type Host Address Life [sec]   ------------------------------------------------------------   KEVIN  UNIQUE 200.200.200.3 597   C:>nbtstat -A 200.200.200.3   Local Area Connection:   Node IpAddress: [200.200.200.5] Scope Id: []   NetBIOS Remote Machine Name Table   Name Type Status   ---------------------------------------------   WORKST2  UNIQUE Registered   SAVILLTECH  GROUP Registered   WORKST2  UNIQUE Registered   WORKST2  UNIQUE Registered   SAVILLTECH  GROUP Registered   WORKST2  UNIQUE Registered   WORKST2  UNIQUE Registered   KEVIN  UNIQUE Registered   MAC Address = 00-08-C3-8F-0D-83

From this information, I discovered that Kevin is using machine WORKST2 at IP address 200.200.200.3.