Performance and SEO impact of not rewriting your urls to use or not use www

Here's a quick tip which will influence your performance and SEO. It's just about uncommenting 2 lines of code in the .htaccess file that ships with Drupal (and replacing some text), but I've seen a lot of sites that tend to forget this.

Suppose your domain is something like yourdomain.com. Check now if you can access your site by prefixing your domain with www. and by not doing it. So check if http://www.yourdomain.com is accessible and if http://yourdomain.com is (without redirection to one of the two). If so, this article is for you.

The problem

If you have Drupal's page cache enabled, 2 cache entries will be generated for your page if you visit the same page on http://www.yourdomain.com and http://yourdomain.com. This is because the cache key Drupal generates is based on the full url (well, actually the cache key is the full url). This means your cache hit rate will be lower and the performance gain you'd get from caching will be not as high.

Another issue with this is that this will have some impact on your search engine results ranking. Suppose half of the people use the www-less domain, and the other half will use the www-having domain, then the score of your page for search engines will be shared between the two pages.

The solution

How can you solve this? Easy. Open your Drupal installation's .htaccess file and look for the following part.

  # If your site can be accessed both with and without the 'www.' prefix, you
  # can use one of the following settings to redirect users to your preferred
  # URL, either WITH or WITHOUT the 'www.' prefix. Choose ONLY one option:
  #
  # To redirect all users to access the site WITH the 'www.' prefix,
  # (http://example.com/... will be redirected to http://www.example.com/...)
  # adapt and uncomment the following:
  # RewriteCond %\{HTTP_HOST\} ^example\.com$ [NC]
  # RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
  #
  # To redirect all users to access the site WITHOUT the 'www.' prefix,
  # (http://www.example.com/... will be redirected to http://example.com/...)
  # uncomment and adapt the following:
  # RewriteCond %\{HTTP_HOST\} ^www\.example\.com$ [NC]
  # RewriteRule ^(.*)$ http://example.com/$1 [L,R=301]

If you read the comments in this part, you'll know what to do. Just uncomment the 2 lines that apply to your case (would you like to use the www-having or the www-les urls?).

For example, suppose my domain is mydomain.com and I would like to redirect all my urls to the www-having domain I would do the following:


RewriteCond %{HTTP_HOST} ^mydomain\.com$ [NC]
RewriteRule ^(.*)$ http://www.mydomain.com/$1 [L,R=301]


Caveat

Just a little caveat. If you update your Drupal installation, the .htaccess file will be overriden (unless you don't explicitly don't overwrite it). In case you override your .htaccess file when updating, just make sure you redo these modifications.