Example a ( C # HTTP request sent by proxy ): https://q.cnblogs.com/q/88682/
Example Two ( C # Agent HTTP request ): https://www.cnblogs.com/ShalenChe/p/5405013.html
Example Three ( C # HttpWebRequest used in the domain name request specifies the IP Proxy is implemented ): https://www.cnblogs.com/greenerycn/archive/2010/04/11/httpwebreques_host_modify_By_set_proxy.html