redirect subdomain to another domain - redirect

Question

Current i am using windows shared hosting. I need to redirect my sub domain to a new domain(including the entire path).
For example, when user visit to http://oldsubdomain.olddomain.com/page1/topic1 , it will redirect user to http://newdomain.com/page1/topic1
This is the method suggest by my service provider
<script language="c#" runat="server">
private void Page_Load(object sender, System.EventArgs e)
{
Response.Status = "301 Moved Permanently";
Response.AddHeader("Location","http://www.new-url.com");
}
</script>
But this way seems like not able to redirect the entire url. Any suggestions?
Thanks
*UPDATE
Trying to redirect using web.config as below, but still get 500 Internal error, any idea?
<?xml version="1.0"?>
<configuration>
<system.webServer>
<rewrite>
<rule name="CName to URL" stopProcessing="true">
<match url=".*" />
<conditions>
<add input="{HTTP_HOST}" pattern="^(?!www)(.*)\.olddomain\.com$" />
</conditions>
<action type="Redirect" url="http://newdomain.com/{R:0}" />
</rule>
</rewrite>
</system.webServer>
<system.web>
<compilation debug="false" targetFramework="4.0" />
</system.web>
</configuration>

Answer 1

Why not use the redirect method?
private void Page_Load(object sender, System.EventArgs e)
{
response.redirect("http://newdomain.com/page1/topic1");
}