Having multiple domains direct to one web site

Recently I've consolidated a few domain names that I've acquired to direct to this site, and a few others to direct to another site that I maintain. One of the things that I wondered about after I set things up in the sites control panel to receive requests as the other domain names was how that might effect search engine positioning.

What I found was that it most likely would cause more harm than good since most search engines penalize duplicate content. The best scenario would be that the search engines would pick and choose which combination of domain/page would be the most relevant. I would have little control over it. There is, however, a way to redirect them in a way the search engines can understand that it's the same site and not penalize you. This is done within the .htaccess file. Now I've talked about the .htaccess file once before with regards to password protecting a directory and doing custom error pages. In this case (if you don't already have one). Create an empty text file in your home directory called .htaccess and add the following lines to it.

RewriteEngine On

RewriteCond %{HTTP_HOST} ^(www.?)yournewduplicatedomain.com$

RewriteRule ^(.*)$ http://www.yourprimarydomaincom/$1

Save it and test, you should be set (as long as you've already got the domain pointing to your nameservers and you're site is configured to accept traffic for that domain as well (your nameserver knows about it.)