socket.io不断尝试在错误的地址上使用轮询

嘿,我正在尝试使用socket.io与跨域.例如,假设域名是:https://client.domain.com和https://server.domain.com.我的客户端代码如下所示:

socket = io.connect("https://server.domain.com");
socket.on("connect", function () {
    console.log("socketio Connected to server!");
});
socket.emit("test", {"test":"test"});

和服务器端:

var fs = require('fs');
var https = require('https');
var express = require('express');
var socketIO = require('socket.io');
var app = express();

// Settings
var serverOptions = {
  key: fs.readFileSync('privkey1.pem'),
  cert: fs.readFileSync('cert1.pem')
};

var serverPort = 443;

// Logic
var server = https.createServer(serverOptions, app);
var io = socketIO(server);

io.on('connection', function(socket) {
  socket.on("test", function(data) {
    console.log(data);
  });
});

server.listen(serverPort, function() {
  console.log('server up and running at %s port', serverPort);
});

一切正常,消息来回发送.但有些reasone socket.io一直试图使用轮询和错误的域.几乎每一秒我都看到这些要求:

Request URL:https://client.domain.com/socket.io/?EIO=3&transport=polling&t=1452418594321-145
Request Method:GET
Status Code:302 OK

为什么socket.io这样做,我怎么能关闭它？

编辑:更有意思的是,如果我注释掉所有与socket.io相关的代码并且只留下它仍然继续制作前面描述的这些HTTP请求.

编辑2:不确定这是否会产生任何差异,但实际上域名不是一个域的子域名.他们是https://clientdomain.com和https://serverdomain.com.