Your computer is unable to access external names or IP addresses. You need to connect to external Internet resources.  What should you do first？（）

A.In a command window， type the ipconfig /displaydns command.

B.In the Network and Sharing Center window， click the View Full Map link.

C.In the Network and Sharing Center window， click the Diagnose and repair link.

D.Configure the DNS server by using an IP address provided by your Internet Service Provider （ISP）.