Ajax错误响应为时已晚？

Ajax function error response (Network error occurs) waiting for 1 min. If any function to quickly get for error response?

var $this=$(form);
 $.ajax({
    url: 'http://www.example.com/post.php',
           dataType: 'text',
            cache : false,
            crossDomain : true,
           type: 'post',
           contentType: 'application/x-www-form-urlencoded',
           data: $this.serialize(),
           async:false,
           success: function( data, textStatus, jQxhr ){
               alert(textStatus);
           },
           error: function( jqXhr, textStatus, errorThrown ){
               alert(errorThrown);
           }
      });
     return false;