下面域名都是有效CDN域名，指向相同文件

• assets.zhihuishu.com
• assets-1.zhihuishu.com
• assets-2.zhihuishu.com
• assets-3.zhihuishu.com
• assets-4.zhihuishu.com
• assets-5.zhihuishu.com
• assets-6.zhihuishu.com
• assets-7.zhihuishu.com
• assets-8.zhihuishu.com
• assets-9.zhihuishu.com