URL_Rewriting with ISAPI_rewrite

I have a problem in ISAPI_rewrite 3.

a have a url like

www.example.com/web/index.html?ag=2154

What I want is, when the user writes this address it should be converted to agent's subdomain like

www.2154.example.com/web/index.html?ag=2154

Thanks i开发者_开发知识库n advance

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Do you want the URL in the address bar to change or do you want it to be converted "behind the scenes"? Please try either

RewriteBase /
RewriteCond %{QUERY_STRING} ^ag=(\d+)$ [NC]
RewriteRule ^web/index\.html$ http://www.%1.example.com%{REQUEST_URI} [NC,L]

or

RewriteBase /
RewriteCond %{QUERY_STRING} ^ag=(\d+)$ [NC]
RewriteRule ^web/index\.html$ http://www.%1.example.com%{REQUEST_URI} [NC,P]