A为主站点

B为A的应用程序站点

再A的web.config中对不想继承的节点用location 套起来。如下：

 <location path="." allowOverride="true" inheritInChildApplications="false">

    <appSettings>.....</appSettings>

    <connectionStrings>....</connectionStrings>

    <system.web>.....</system.web>

 </location>

参考资料：

http://www.leadnt.com/asp-net%E7%BD%91%E7%AB%99%E5%9C%A8iis%E4%BD%9C%E4%B8%BA%E5%AD%90%E5%BA%94%E7%94%A8%E7%A8%8B%E5%BA%8Fweb-config%E7%BB%A7%E6%89%BF%E6%80%A7%E9%97%AE%E9%A2%98.html

http://www.csharpwin.com/dotnetspace/13433r7850.shtml