When setting up a new website in Plesk 11 (version 11.5), the default domain domain setting will be to use the non-www version of the domain. i.e. http://example.com rather than http://www.example.com
This is easy to change in Plesk 11 and saves having to use alternative redirect methods such as a .htaccess redirect. Under websites and domains, select ‘Hosting Settings’ next to the domain.
Under the ‘preferred domain option’, there will be 3 choices:
The first option should be selected if you want to set your domain to be appended with ‘www’ by default. This will also redirect the non-www to the www. Select the second option to use the non-www if you prefer, which will redirect the www. Selecting ‘None’ will mean both the www and non-www will be accessible as neither of them will get redirected.
I would always recommend however that you redirect either the www or non-www to the other as this helps to avoid ‘canonicalization’ issues – the process of picking the best URL when there are multiple options. If neither the www or non-www aren’t redirecting, Google and other search engines could treat both versions differently.
Setting the www or non-www this way in Plesk uses a ‘301 redirect’. This tells search engines that the site has permanently moved which is best for SEO purposes.