Q: In summer 2006, my website had 11,000 pages indexed in Google. But that number has started decreasing and I don’t know why. The site has new pages added every day.

I manage this site with cpanel [a domain hosting and management system], and a few months ago I decided to park a second domain in my site account. I don’t know why but suddenly I started to see pages of my site indexed at Google with this second domain, instead of the first domain…I don’t know if this was good or bad to my ranking, but I thought it could be bad because if Google was indexing pages in this second domain, it could not be indexing pages with the first domain…

I am afraid that if it continues like this the site will have no indexed pages left! Do you know why this is happening?

A: What you describe could be a problem with Google seeing both of your URLs as unique domains, and indexing them as if they are two separate websites. The reason that this is a problem is twofold: (1) it splits your “page authority” values between the two sites, to the detriment of both, and (2) Google and other search engines may interpret your pages as duplicated content, and remove the duplicated pages from its index for one or both URLs.

Our suggested next step is to sign up with Google Webmaster tools and do the following:

• Set up an XML Google SiteMap for your primary domain
• Create a robots.txt exclusion file and exclude the secondary domain from indexing
• Set a preferred version of the URL (we recommend with the www )

Meanwhile, check in with your hosting service or webmaster on a few other potential issues:

• Be sure that the secondary domain is redirecting to the primary domain using a 301 server-side redirect
• Make sure that “domain masking” (if that’s an option in your hosting service) for the parked domain is OFF.

If you do all of this, we think it will either clear up the problem or provide valuable information about the problem (ie, possible indexing errors such as spider traps – infinite dynamic pages loops that flummox search engine spiders – or unreachable pages).

If it turns out that there isn’t actually an indexing or duplicate content problem, your website may just need more energy devoted to a holistic SEO promotion as we describe in our SEO book. Google may have put your pages in their “supplemental” index based on a very low number of links pointing to them or because Google in its own inimitable way has decided that these pages are less valuable than your other pages. Working toward more inbound links to your deeper pages is always a great idea, regardless. Good luck!