如要将8a.hk重定向到www.8a.hk，则配置web.config如下：

<?xml version="1.0" encoding="UTF-8"?><configuration><system.webServer><rewrite><rules><rule name="www" stopProcessing="true"><match url=".*" /><conditions><add input="{HTTP_HOST}" pattern="^niaoyun\.com$" /></conditions><action type="Redirect" url="http://www.niaoyun.com/{R:0}" redirectType="Permanent" /></rule></rules></rewrite></system.webServer></configuration>