Wildcard Subdomains

May 12th, 2007 by Michael Gray in SEO

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Yesterday I stumbled across a curious subdomain, after poking around I discovered it was actually a wildcard subdomain implementation. So I had a bit of fun playing with Jason Calacanis but then discovered it’s really a bug that’s present in all of the weblogs inc blogs.

If you’ve ever been to a site clinic one of the things you’ll often hear people get told to fix is having a “www” and non “www” version of the site. The logic being that is you can create two versions of your website, creating duplicate content for yourself, and hoping the algorithm figures it out. In Google’s defense they do let you specify that in webmaster central but that’s still really not a best practice, and lets not forget there are other engines like Yahoo, MSN and ASK.

When you are building the structure of a site you can do it a few ways one with subdomains and one with folders for example:

example.com/widgets/
widgets.example.com

There are advantages and disadvantages to both, but that’s another discussion for another time.

With wildcard subdomains you can change the “widgets” in the example above to to any other word and the backend will adjust accordingly, for example:

widgets.example.com
hammer.example.com
screwdriver.example.com

What’s supposed to happen is your programming “reads” the subdomain and serves up unique content based on that particular subdomain. One of the mistakes some people make are not properly implementing 404 in case of jibberish words such as:

asdf.example.com

The worst way to handle this error is to serve the exact same content for any subdomain, for example the content for the following two URL’s would be exactly the same

widgets.example.com/blue/
teletubbies.example.com/blue/

This is exactly what is happening on Jason Calacanis domain for example:

http://passthedoritos.calacanis.com/2007/04/26/fatblogging/
http://mmmtwinkies.calacanis.com/2007/04/26/fatblogging/
http://iluvdirtydancing.calacanis.com/2007/04/26/fatblogging/

This isn’t a problem just for Jason’s domain it’s also a problem for the entire weblogs inc network, for example:

http://anywordiwant.engadget.com/2007/05/12/students-bring-pong-and-lasers-together-at-last/

where the problem grows geometrically is how the software builds the urls. Some use a hardcoded/programatically driven value others work off of the current page, to see it in action go to the section area in the sidebar shown in the screen shot on the right and click away. The spiders will come along and find multiple versions of the same content, spider them and keep going, and that’s not what you or the search engines want. If you don’t believe go ahead ping Matt or Adam at Google.

Ok Jason I know you don’t work at/for/with weblogs anymore but I’m sure you can still pick up the phone and make things happen, I’d do it sooner than later before somebody gets a subdomain like this one into the index. It’s kind of funny how you get them most free SEO advice for someone who hates SEO’s, I guess maybe some of us are good folks who actually do help people, and aren’t just interested selling silicon based snake oil, something you might want to think about …

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