Subdomains vs. subdirectory – status as of 2012. [duplicate]

Question

This following question by Jeff was in 2010 and I wanted to check how things have changed in the past 2 years.
My problem:

I run a site with most of the content distributed to subdomains that’s are user based. E.g:

Joe.example.com
John.example.com
Jil.example.com 

So all of these subdomains have the content and the main site example.com becomes a mere dummy listing all the subdomains.
Now the question is, as of 2012, how is google treating domain authority and page rank in this case?
I understand the notion of page rank as page per se but when it comes to domain authority will the parent domain have the cumulative effect of the domain authority or will it be spread out?

Answer 1

Google does use domain authority to rank sites, or at least they use the Panda update to demote pages on a site-wide basis. From Google's original announcement in 2011:

This update is designed to reduce rankings for low-quality sites—sites which are low-value add for users, copy content from other websites or sites that are just not very useful. At the same time, it will provide better rankings for high-quality sites—sites with original content and information such as research, in-depth reports, thoughtful analysis and so on.

However, it is unclear how that affects subdomains. It is generally believed that subdomains do not benefit from the domain's overall status - otherwise every tumblr, wordpress, and blogspot would benefit from the primary domain's high authority. (Or, conversely, all the low-quality wordpress blogs would kill the main site's rankings due to Panda) Additionally, there is some evidence that websites have been able to escape Panda site-wide demotions by moving content to subdomains. Yet at the same time, a Google employee has recently implied that subdomains and subdirectories are treated the same for SEO:

(Q) The next big question is should I use sub domains instead of sub directorys for the 27 different eu countries we will be targeting. I hear sub domains are better for SEO purposes?

(A) We generally treat subdomains the same as subdirectories in that regard, both can use geotargeting. Sometimes one or the other is easier with your CMS or hosting, so I'd make that decision based on whatever works best for you :)

Overall I think the general evidence suggests that subdomains are treated independently, or at least mostly independently, of their overall domains, but you can also find statements and evidence that hint at a connection as well. Ultimately, we just don't know.

Answer 2

I wouldn't primarily think about Google's web-search algorithms when designing a website in that regard -- you're unlikely to see a visible effect in web-search either way.

Using a single host name can make things easier to track in an aggregated way (eg in Webmaster Tools) if these are all a part of your website. Similarly, if these are for user-generated-content by individual users, then it can make it easier for them to track their "own" if you use subdomains and allow them to use Webmaster Tools.

My recommendation would be to pick the model that works best for you and your users; Google can handle either way fairly well.

Answer 3

The domain authority is only a constructed metric, giving a general idea of how powerful that domain is in Google's eyes, but the only thing that matters is PageRank. Google does not use domain authority to rank the sites (I don't even think they compute that).

The advantage of having lots of subdomains is that you can interlink them and it would be considered an internal link, so PageRank can flow from page to page (if you have one really popular page, but it interlinks with other pages, the less popular ones will benefit from this).

However, nothing has changed in this aspect compared to 2 years ago.