如要将niaoyun.com重定向到www.niaoyun.com，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="^24iis\.com$" />
</conditions><action type="Redirect" url="http://www.24iis.com/{R:0}" redirectType="Permanent" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>