You are the administrator of ExamSheet.net's network. ExamSheet upgrades its network to 100 Mbps. You remove the old network adapter and install a new 10/100 Mbps network adapter into a Windows 2000 Professional computer. You configure the TCP/IP protocol settings so that IP and DNS addresses are obtained automatically. When you restart the computer you cannot access the network. When you attempt toPINGaddress 127.0.0.1 you receive the following error message: "Request timed out." You want this computer to communicate on the network. What should you do?（）

A. Configure IP address settings manually.
B. Replace the network adapter.
C. Disable TCP/IP filtering for all network adapters.
D. Configure DNS server address settings manually.
Enable IEEE 802.1x authentication.