tuning htAccess to avoid duplicated content and avoid problems with google panda & co?

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Google

SEO

web_development

Hello all,

Introduction and code sample:
A friend of mine told me that I should update the HTACCESS of our company site to avoid giving duplicate contents to Google, his recommendation would be to update the .htAccess file adding these lines:

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

RewriteCond %{HTTP_HOST} ^codeproject.es [NC]
RewriteRule ^/?(.*) http://www.codeproject.com/$1 [R=permanent,L]

The idea here would be to tell the indexing spiders not to index all the domains we have as if they would have different contents redirecting the spiders to the main domain.

Of course I've tried to change the htAccess to see which would be the result, but nothing seem to be updated so I've went back to the original one...

I'm worried on the real impact of having multiple domains that seem to be pointing to the same content, if he is right, then we have a problem.

I can understand the main idea and I can even understand the code lines that I've put into the htAccess file, but how can I be sure that the hosting company has not done anything to avoid this wrong situation by themselves at the moment of buying the domains?

Note:
In one recent comment, It has been recommended me to use "robots.txt" to avoid that. As far as I know, this is not what I need as "robots.txt" is used to tell the spiders what files to crawl and what files to avoid crawling. In my case, I have multiple domains that point to the same web pages, therefore, it is like I would have different web pages with the same content and that would mean to be punished by Google as it can be understood as a black hat SEO technique. This is the reason why my friend recommended me to use that 301 redirect.

Questions:
Is there any way to know if we are being punished by Google?
Any hint?
A good explanatory link?

If I want to avoid Google punishment and keep my different domains pointing to my main domain, which would be the correct way of doing it?

As always thank you in advance. :thumbsup: