Drupal and Canonical URLs

Google Engineer Matt Cutts talks about canonical home page URLs on his blog. The concept is basically this:

For the most part, search engines view different URLs as being entirely different pages. So the following URLs all may show the same content, but search engines will often see them a different pages with duplicate content:

1. http://example.com
2. http://www.example.com/
3. http://example.com/index.php
4. and so on...

Drupal does not link to its index.php file so the third URL example is generally not an issue with Drupal. However you should choose between using the www version of the domain name or the non-www version of the domain name. Drupal makes this easy by providing instructions in the default .htaccess file as shown below:

# adapt and uncomment the following:
# RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
# RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
#
# To redirect all users to access the site WITHOUT the 'www.' prefix,
# (http://www.example.com/... will be redirected to http://example.com/...)
# adapt and uncomment the following:
# RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
# RewriteRule ^(.*)$ http://example.com/$1 [L,R=301]


When setting up your Drupal site you should decide whether you want your site to have the www subdomain or not and choose one of the two options in the .htaccess file.

For SEO purposes it doesn't matter either way unless your site has already been live for a while. If Google has indexed your site and shows the PageRank value of the home page (as seen in the Google Toolbar or through a Firefox Extension like Search Status), then Google has already chosen one version or the other for your domain name. In that case I would redirect to the version of the domain that Google has already accepted. You can determine which version Google has chosen by typing your domain name into Google without the www like this: example.com

Google should show your domain name at the top of the SERPs. If Google shows your home page with the www then you should redirect your site to the www-version. If they leave off the www then redirect to the version without the www.

Some people would say that it doesn't matter which one you redirect to even if Google has already indexed the site. But sometimes when you 301 redirect pages or sites, Google drops the original URL and it takes a while to get it ranked again. That is why I recommend going with the choice that Google has already made for you.