IIS Web.config: redirect non-www to www

To redirect requests without the www to www on your website, add the following rules to your web.config.
Make sure your.domain.name below is changed to your domain name.
NOTE: If you already have a web.config with rules configured, add the rule below, otherwise a full web.config example is below it.

Rule
=========================================================================

        <rule name="Redirect to WWW" stopProcessing="true">
          <match url=".*" />
          <conditions>
            <add input="{HTTP_HOST}" pattern="^your.domain.name$" />
          </conditions>
          <action type="Redirect" url="http://www.your.domain.name/{R:0}" redirectType="Permanent" />
        </rule>

Full Web.Config with Rule
==========================================================================

<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="Redirect to WWW" stopProcessing="true">
          <match url=".*" />
          <conditions>
            <add input="{HTTP_HOST}" pattern="^your.domain.name$" />
          </conditions>
          <action type="Redirect" url="http://www.your.domain.name/{R:0}" redirectType="Permanent" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

thanks.   I have multiple websites.  is there a catch all?

What do you mean multiple websites ?
Are they on same domain ?

Redirection is working from non www domain and forwarding request to www.doman.com
If you have few websites with different name like

www.domain.com
www1.domain.com
www2.domain.com
then you need to create more rules but if user will put http://domain.com in browser then only first rule will work.

you could use the redirection function in IIS. See the link below

https://technet.microsoft.com/en-us/library/cc770409(v=ws.10).aspx