(The XP client requests the DC for its own certificate, and the XP terminal requests the computer certificate. When the XP terminal connects to the communication machine with 802.1X authentication turned on, it logs in once and obtains the IP address. The experiment requests that testuser2 can log in to the XP terminal, but testuser1 cannot log in to the XP terminal. Note: This experiment requires deployment in accordance with enterprise practice, requiring equipment to be an independent root CA server and an enterprise sub-CA server to be installed.)