Use KMS with Proxy Server
There're two solutions for using KMS with proxy server, please check the information as below:
a. Please refer to this link http://technet.microsoft.com/en-us/library/hh824906.aspx.
b. Please open IE, click the "Tools" in the menu bar-> click the "Internet Options"-> "Connections"-> "LAN Settings-> select the "Bypass proxy server for Local address" check box (Figure 1-1).