Earlier this week, Google webmasters tools sent an alert which concerns when a specific URL doesn't appear and is considered as a URL duplicate on a different domain. On its blog post, Google Webmaster Central detailed how duplicate content is identified. Google determines how they opt to pick the canonical version over the URL carrying duplicate or borrowed content. Such scenario isn't new anymore because some businesses increase their SEO by buying several domains but putting the similar content from their original site.

As Google began its Panda clean-up, the issue of duplicate content is a crucial issue for SEO experts and webmasters. With the help of its algorithms, Google chooses a single representative URL for a particular set of content. The selection is called cross-domain URL selection. Google cites this example:

“To take a simple example, if the group of URLs contains one URL from a.com and one URL from b.com and our algorithms select the URL from b.com, the a.com URL may no longer be shown in our search results and may see a drop in search-referred traffic.”

Site owners could use rel=”canonical” elements or 301 redirects in order to specify their preferred URL. Some webmasters won't make use of options to specify their URL though which makes Google choose a version. Most of the time, Google's algorithms select the URL version that the site owner prefers. Common causes of unexpected cross-domain URL selections are:

  • Incorrect canonicalization
  • Multi-regional websites
  • Hacked sites
  • Misconfigured servers
  • Sites with scraped content

Check out this guide on how to fix the issues. Webmaster Central will send new messages to promote transparency regarding cross-domain URL selection decisions. These will notify webmasters and site owners if Google's algorithm picked an external URL rather than one from an owner's website. Google Webmaster Central also has its help forum in order for webmasters and site owners to ask a query or discuss an issue.