.htaccess http://www. and http:// : what is the influence for SEO?

I am trying to improve my SEO rank : I use http://www.woorank.com tool I have a "sever error" that tells me:

Be sure that http://roulette-chat.fr and http://www.roulette-chat.fr are not running in parallel.

Redirecting requests from a non-preferred hostname is important because search engines consider URLs with and without "www" as two different websites.

Once your preferred domain is set, use a 301 redirect for all traffic to your non-preferred domain.

Can someone tell me how t开发者_JAVA技巧o solve this issue with the .htaccess ? regards

Replace example.com with your domain name.

RewriteEngine On
RewriteCond %{HTTP_HOST} !^example\.com$
RewriteRule ^(.*)$ http://example.com/$1 [L,R=301]

Alternatively, if you want to force the 'www' use:

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

There are plenty of people in the no-www camp (I used to be one), but remember this can limit the use of sub-domains.

By redirecting one to another (no-www to www or vice versa), you effectively consolidate backlinks to one version of your domain. The major search engines treat www and no-www as seperate pages. You can also make use of the rel=canonical link element as described here: http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html