Microsite on subdomain vs. subdirectory

[ryanwats]

Based on this post from 2009, it's recommended in most situations to set up a microsite as a subdirectory as opposed to a subdomain. http://www.seomoz.org/blog/understanding-root-domains-subdomains-vs-subfolders-microsites.  The primary argument seems to be that the search engines view the subdomain as a separate entity from the domain and therefore, the subdomain doesn't benefit from any of the trust rank, quality scores, etc.  Rand made a comment that seemed like the subdomain could SOMETIMES inherit some of these factors, but didn't expound on those instances.

What determines whether the search engine will view your subdomain hosted microsite as part of the main domain vs. a completely separate site?  I read it has to do with the interlinking between the two.

[Conor_OShea_ETUS]

I think the footer is the best way to interlink the websites in a non-obtrusive way for users.  This should make your main corporate site your top linking site to each subdomain - and this is something you should be able to verify in a tool like Google Webmaster Tools.  I do not have any specific examples to support this, but this is a common web practice.

This is not 100% related, but Google recently suggested using Footer links as one way to associate your web content with your Google profile account:

http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=1408986

So you can figure if Google looks to footer links to associate authorship - they would likely do the same to relate sites together.

[Svetoslav]

Hi Ryan,

Your question is quite interesting. I, myself, went through the article one more time. I have no facts to back up the following, but I hope that it will contribute. FIrst I would go and validate them on webmaster tools. If they are inteded to hit a certain market, I will select that geographical location. Also, I think you have litte to worry about. I imagine that google won't pass certain trust to subdomains, depending on the site. If the number of subdomains is considerable, I would say that they have pretty slim chances of getting some push from the main site. Take for example free webhosting services. They could rank and have decent page rank, if people show interest to the particular subdomain, but is highly unlikely taht to be caused by the authority of the main site.

I haven't seen free hosting subdomain rank well for a long time now. On the other hand you have student and academic accounts on university sites. They all go with subfolders and rank pretty well for highly specific topics. If I have to give a short answer, I would say that is the type of site that makes the difference for google. If your site is considers a casual business website and you are developing a new market then you might not have a problem. If you use sudbomains for specifying product, then you might be ok again.

Google use subdomain for all their major products. For Google pages they used a separate domain. They now redirects to a subdomain sites.google.com. However, they will never give subdomains for personal use. There might be something to that. They do a 301 redirect from a subdomain on googlepages.com to sites.google.com/site/. So what they offer is a 301 redirect to a sub-sub folder, located on a subdomain on Google.

[ryanwats]

Ok. That makes sense. The way our company would use it is having a microsite for specific, focused topics - large enough that warrant their own site.  They are clearly part of our overall brand, unlike the Disney properties example.  On each of these sites, there will almost always be a link back to the main/corporate website, usually in the footer.

Do you think having one or two links on every page pointing back to company.com would be sufficient to notify search engines that the two are associated, and ultimately give some search value to the subdomain hosted microsite from the main domain?

Are there any studies or evidence supporting any of this?

[Conor_OShea_ETUS]

Interlinking is definitely a factor - but content is what matters.

Take the Disney brands that live on Go.com:

Espn.go.com

Abc.go.com

Abcnews.go.com

They all live on Go.com but Google surely knows they are really separate sites that cover different topics.  Same for any blogspot.com, typepad.com, etc. hosted blog.  The millions of blogs there cover a wide range of topics and search engines understand that they are not related just because they share the same host domain.

On the other end of the spectrum - if your site just has two subdomains - let's say www.website.com and blog.website.com ... which cover the same topics and link to one another, search engines would more likely associate those two addresses.

[john4math]

I don't have an answer to your question, but if you're looking for some more reading about subdomains vs. TLDs, here is a presentation given at MozCon: http://www.distilled.net/blog/seo/mozcon-international-seo/. The slideshow has some info about it, and a bunch of other good stuff.