Subdomains are now considered internal links by Google Webmaster Tools
Google’s webmaster blog announcement a drastically significant change in the way Google Webmaster Tools categorizes subdomains.
Previously, subdomains would be considered separate sites and therefore a link from a subdomain would be considered an external link by Google, in Google reports. Today Google is changing that and now considers these internal links.
So when I link from forums.seroundtable.com to www.seroundtable.com, it’s no longer a link from an external domain, it’s a link from an internal domain.
Most people think that example.com and www.example.com are the same site nowadays, we are changing it so that now if you add example.com or www.example.com as a site, the links of both the www and non-www versions of the domain will be classified as internal links. We also extended this idea to include other subdomains, as many people who own a domain also own its subdomains. Thus, links from cats.example.com or pets.example.com will also be classified as internal links for www.example. com.
Here is the table they used to explain it:
|Links for www.google.com||external links||Internal links|
|Previously classified as …||www.example.com/
|Now classified as …||www.example.com/
So does this have an impact on how Google treats subdomain links in its linking algorithm? I think so. Hubpages played on it and said it helped with Panda.
Does that mean Google will list fewer of your subdomains in search results as individual results? Well, yeah – they’ve already done that with the new mega sitelinks, which interestingly doesn’t apply to finding [google].
Either way, note this big change, not only in the reporting in Google Webmaster Tools, but also in the way it defines search results, linking algorithms, etc.
Discussion forum at WebmasterWorld.
Update: Google clarified that this has no impact on rankings. See more details here.