Here's my contribution to the "I found something new and weird on Google today" file.
I've had a personal website up on a "myname.com" domain for a decade. It's not large, just a short math tutorial with about a dozen static, .shtml pages that I've not updated, save for style changes, in years.
About seven years ago, I started a new section of the site, devoted to reader ratings and grassroots journalism covering a niche travel industry. Within a year, the section grew to the point where I bought a "keywordphrase.com" domain for it. But I kept it on the same server -- same IP. The site was written in ColdFusion, so I used CF code in my index.cfm to serve the keywordphrase content to requests for that home page, while giving the old myname.com content to those requests.
Over the years, the pages on "keywordphrase.com" have performed well on Google SERPS for a variety of destination keywords in this travel niche. But about two years ago, I noticed that while the site placed within the top 5 for "destination-name keyword" for many popular destinations, it had slipped from the top 100 results for "destination-name keyword" for the single most popular destination in the niche.
The paranoid in me suspected some sort of penalty, as my site's Toolbar PR far outranked almost all of the sites listed ahead of my page on that topic in the SERPS. But I've never done anything black hat. And yes, I know that everyone says that. But this site has won a major journalism industry award, been a finalist for a Webby Award, been featured on major TV network news shows and been named best in its niche by several top travel and business magazines. I don't need to do black hat to get traffic.
Yet, our coverage has ticked off people in the industry, and it would not surprise me to see that someone at one of the companies we've covered engage in some black hat SEO to move us down inthe SERPS. Especially for the ultra-valuable phrase "destination-name keyword." But I never could prove anything.
So much for background. Here's where things get interesting. Last week, I noticed that my page was back, after two years, in the top five for that top "destination-name keyword." Except that now the domain name to the page was "myname.com" instead of "keywordphrase.com." (It's the same page though. And I'd never done a 301 redirect from myname.com to keywordphrase.com for that page because I'd never linked to that page using the myname.com domain.)
I was enjoying the extra revenue that this strange move up the SERPS brought, until today. That's because the a Google search for "keyword phrase," which up until today brought up the "keywordphrase.com" home page in the number two slot, today brings up "myname.com" home page in that spot. With the title, blurb and cache for the myname.com home page. "Keywordphrase.com" is nowhere to be found in the SERPS for "keyword phrase."
Click-through, predictably, has plummeted, as no one searching for "keyword phrase" cares to see a personal site with a math tutorial.
It's as if Google taken all the value of the incoming links to keywordwordphrase.com using the keyword phrase and assigned it to myname.com, a site that's never been linked to using those keywords. All I can figure is that since a request for the IP address served by the myname.com page (given how I set up the index.cfm page), Google must now be figuring that myname.com is the canon domain for the site, so it is overruling the domain specified in the navigation for keywordphrase.com. Which would make hosting two domains on the same IP pretty much impossible.
It also suggests to me that there was some sort of domain-specific penalty applied to my "destination-name keyword" page, that was wiped away when that page was indexed under another domain. (Which opens up a pretty massive exploit for the black hat crowd.)
In both cases, yikes.
I throw myself on the collective expertise of the board for answers as to what the heck is going on here. Thanks.