Setttings for redirect site to www

If you have hosted a site, suppose domain name is www.radhekrishna.com. But when you will open radhekrishna.com without writing www then it will also works. And it will also works for www.radhekrishna.com but both site have his different cookies.
 
So if you want to alwasy redirect your site to www.radhekrishna.com event if have written the www or not then you have to do a setting in config file.         
  1. <configuration>   
  2.   <system.webServer>   
  3.     <rewrite>   
  4.       <rules>   
  5.         <rule name="Redirect to WWW" stopProcessing="true">   
  6.           <match url=".*" />   
  7.           <conditions>   
  8.             <add input="{HTTP_HOST}" pattern="^radhekrishna.com$" />   
  9.           </conditions>   
  10.           <action type="Redirect" url="http://www.radhekrishna.com/{R:0}" redirectType="Permanent" />   
  11.         </rule>   
  12.       </rules>   
  13.     </rewrite>   
  14.   </system.webServer>   
  15. </configuration>