If Subdomain Change Not As Bad As Originally Thought When Should You Use A Subdomain

Technorati Tags: google,subdomain,host crowding,search algorithm

You may have already read that Google’s Matt Cutts went into more detail about changes Google made concerning subdomains. At first, many Internet marketers thought Cutts’ original comment at PubCon meant that no more than one subdomain would appear in the SERP’s for each domain. It turn’s out that the change was actually implemented several weeks before Matt made told audience members in Vegas and has gone pretty much unnoticed. Matt posted a new blog entry Monday that clarified the point of the change. Google is trying to fight ‘host crowding” - many SERPs coming from a single domain. Matt emphasized that the changes won’t effect every search. If a subdomain is relevant to a query it can still show up even if more than two subdomains are already included in the results. Here’s the relevant quote from Matt’s post:

For several years Google has used something called “host crowding,” which means that Google will show up to two results from each hostname/subdomain of a domain name. That approach works very well to show 1-2 results from a subdomain, but we did hear complaints that for some types of searches (e.g. esoteric or long-tail searches), Google could return a search page with lots of results all from one domain. In the last few weeks we changed our algorithms to make that less likely to happen in the future.

This change doesn’t apply across the board; if a particular domain is really relevant, we may still return several results from that domain. For example, with a search query like [ibm] the user probably likes/wants to see several results from ibm.com. Note that this is a pretty subtle change, and it doesn’t affect a majority of our queries. In fact, this change has been live for a couple weeks or so now and no one noticed. The only reason I talked about the subject at PubCon at all was because someone asked for my advice on subdomains vs. subdirectories.

To read the full subdomains and subdirectories post on Matt’s blog click here.

After all the noise Matt’s comments made you may still be confused about when to use subdomains and subdirectories even after the clarification. I think a big area of disconnect is between the way Google expects subdomains to be used and how they’re used by Internet marketers. From personal experience, many marketers use subdomains to host separate sites with different content such as: ringtones.domainname.com, dateingoffers.domainname.com, insurancedeals.domainname.com. Google expects subdomains to offer specific content around a similiar theme or single provider like images.google.com, video.google.com, or groups.google.com. In the first case, marketers shouldn’t be affected since the SERPs those subdomains show up in will come from very different queries. But what about subdomains like ringtones.domainname.com, superringtones.domainname.com, bestringtones.domainname.com, and hotringtones.domainname.com? This is where Google doesn’t want to see a search for “ringtone deals” to return the ringtone subdomains for “domainname.com” in 7 of the top 10 results. If you’ve been doing this, stop. It probably wasn’t working anyway.

Former Googler Vanessa Fox has posted an article that goes into great detail about subdomains and subfolders that should answer all your questions. Check out Vanessa’s post on how Goolge’s subdomain changes could affect you here.

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