How to fix these duplicate content errors

[Oimachi2]

I have some sites that fail duplicate content tests but don't really know how to fix them....

This is on Joomla sites and I can modify the .htacess but how?

Errors #1:

"WWW/NonWWW Header Check: FAILED
Your site is not returning a 301 redirect from www to non-www or vice versa. This means that Google may cache both versions of your site, causing sitewide duplicate content penalties"


"Google indicates that it has "omitted some entries very similar" to the top 1000 pages on your site. This similarity is a duplicate content penalty preventing these pages from being considered uniquely valuable in Google's index."

"You have not standardized your default pages meaning the following versions of your url return a 200/OK Header, which may cause duplicate content issues. "


Google may have duplicate copies of pages on your site due to indexing both the www and non-www version of your site shows 123 pages cached, while the www version shows only 122 cached. Unless your site has subdomains, this often means that some duplicate content penalty may exist."


I wish I could tell you the website's name but webmasteworld won't allow it. There is also a great free tool to do this but again can't say it so if you need to know please PM me.

Cheers!
Bruno

[rocknbil]

This is usually done via .htaccess with mod_rewrite.

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

"If the requested host is not www. example.com, rewrite to the www version and issue a 301 header, don't process any more rules."

Note that the below is what I see in most recommendations around here and other boards:

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

But I can never get it to work like that, only the first two lines, so you may not need it.