I've been following a few SEO discussion groups recently that have been talking about the length of a websites domain registration, and whether or not a short term of registration could negatively affect a websites position in the SERP's (search engine results page).  Now keep in mind, I'm not talking about your domain age, but rather the length of time you actually register your domain for.  Some of the forums have become quite heated, which I found surprising, and obviously nearly everyone has a different stance on this subject.  But is there any truth to this theory?

Well like all of ranking algorithms in place by the search engines, no one except for them really knows for sure whether the length of your domain registration impacts your ranking results.  But there are a few facts that you could keep in mind that could help you gain a better understanding into the mind of the search engines.

1. Domain registration information is easily accessible - and it is easy for a search engine such as Google to find out how long you have registered your domain.
2. Back in 2005 Google patented an application that could find, view and score a website based on domain registration -  http://tinyurl.com/5fpfj (this will show the patent application).
3. The majority of Internet scams and spammers will use throw-away domains i.e. domains that are only registered for a year and then dropped. 
4. Actual domain age most likely outweighs the length of future domain registration.

So with these few little facts, it's easy to see that it is quite possible that Google is looking at the length of your domain registration, and possibly using this information to assist in ranking your site.  But in saying that, I think the ranking influence would be minimal.  Google has 200+ alleged ranking algorithms, and I am sure that they are using other more important factors in judging whether a site is legitimate or not.

While some SEO bloggers are saying things like "length of domain registration is now apart of my site audit"  I believe that the ranking algorithm for this is so minimal, it should not make you run out to extend all of your domain registration times, thinking it will drastically improve your rankings.  However, I do believe that extending your length can give you peace of mind.  If you are a legitimate online business, there should be no harm in registering your domain for 3,5,10 years.  In doing so reducing the risk of overlooking the renewal date of your domain, and all the hassle that goes with it if you do unfortunately forget to renew.

But as with everything SEO, only the search engines have definitive answer.  However I'm going to be monitoring the discussion groups, and will let you know if anyone provides any case studies on their findings.