Redirect Root Domain to WWW Subdomain

The Problem

"When you have two different addresses pointing to the same page, like www.example.com/offers.html and example.com/offers.html, many search engines (or so we are led to believe) will treat those two URLs as two separate pages. When you, as a human, see those two pages and notice they are identical, you will automatically realise (correctly) that they are actually the same page. Apparently, the search engines do not make this assumption, and will regard those as different pages with duplicate content."
(source: www.thesitewizard.com)

I personally think that apart from the SEO problem there shouldn’t be two different urls to the same content in the first place.

So what do we do?

The bad thing to do would be to disable one of the domains (root or www).
We want to select one (www.example.com) as default domain and if someone just enters "example.com" he will be automatically redirected to our default domain.
Again – the bad thing would be to use meta redirects. We want to use so called permanent redirects ( code 301) in order to notify search engines and browsers about the reason we want to redirect.

Using Mod Rewrite

For the cake app to be available per "www.example.com" (and a 301 redirect from mydomain.de) you just need to modify the htaccess file in the /app/webroot/ folder:

<IfModule mod_rewrite.c>
    RewriteEngine On

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

    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^(.*)$ index.php?url=$1 [QSA,L]
</IfModule>

The "localhost" part is not necessary – but it prevents your local htaccess file to redirect on your development computer. That is if you have your htaccess file in svn or git and therefore both versions (local and stage) are the same.

The reason why i did not lay out the other direction (www to root) is simple: I don’t think this makes sense. Most people not so comfortable with the internet usually type the complete address anyway – they just expect a "www" in front of the domain for the main website.
And with the internet getting more and more complex, some guidelines should just remain. One is that you don’t use root domains for websites. (I could go into details here – about other side effects like "technical" cookie problems occuring with root domain sites etc – but i will leave that out for now)

Using Apache Directives

This is way faster because the server doesn’t have to open the htaccess files for it. It can directly use what it has to have available anyway.

Inside /etc/apache2/sites-available/ there should be your domain file.
Between <Directory> and </Directory> you can add the above lines.
To actually increase the performance we now need to disable htaccess files for this domain.
Add AllowOverride None directly above your new lines. This prevents the server from looking for, opening and processing htaccess files.

Note: Usually this is only available on root servers.

Update Cake2.x

For Cake2 you need to slightly change the second rule:

RewriteRule ^(.*)$ index.php?/$1 [QSA,L]