Load Balancing

       01. Different visit the Web site address, the Web page can not be displayed in different   
	proxy_set_header $ Host Host; 
	02. Users access the site address information can not be analyzed statistically       
	proxy_set_header the X-Forwarded-the For-$ REMOTE_ADDR; 
	03. Access Load Balancing get an error page, influence user experience 
	proxy_next_upstream error timeout http_404 http_502 http_403;