One of the quickest ways to kill your search ranking (page rank) with Google is to have duplicate content posted at two domains. For example, exactly the same pages posted at www.site1.com and www.site2.com. Unfortunately Google treats subdomains as separate domains – so if www.site1.com and flop.site1.com have the same content they are treated by Google as duplicate content on two domains. Goodbye pagerank and goodbye search visitors. And Google does not normally treat www. as a special subdomain. So again, content at www.site1.com and site1.com appear to Google as separate domains and hence can create the duplicate content rank killer.
The problem is easy to fix but fix it before it’s a problem!! You can wait weeks for Google to re-index to the point where your search ranking returns. On a cash earning site which relies on search visitors that’s instant death and there is nothing you can do but wait.
No matter which tools you use, the single most important thing to do first is to decide whether you want “www.” or not. Then don’t change it. Trust me, it hurts.
1) Google Webmaster Tools
Google Webmaster tools allow you to select whether www.site1.com or site1.com appears in it’s index. Again, never ever change this once it’s set – this can cause Google to double index as it re-indexes your site, hence creating the duplicate content problem!
2) 301 redirects
There are numerous tools and scripts (including WordPress plugins) which you can use to perform a 301 redirect from the prefix you don’t want to the prefix you do want. Doing this ensures that Google knows which is the permanent page and therefore which one to include in it’s index.
3) Use your host
Both 1&1 and dreamhost allow you to set the 301 redirect automatically. Dreamhost’s redirect control panel options are mind-numbingly easy to use:
In summary, pick one and stay with it. As you grow incoming links, you also want them coming in to the correct prefix. So pick early, fix the problem before it happens and enjoy the income without that horrible sinking feeling that you screwed your pagerank.