That is a very good question and you answered it yourself. Consistency is the key. However, keep in mind that you don’t always have control over how other sites link to yours so implementing the 301 redirect is still a must. http://www. is just another sub domain, it just happens to be the standard default. When you do http://www.subdomain.domain.com, what you are really doing is sub-subdomain.subdomain.domain.com.

The 301 redirect in this case is all about preventing the indexing of duplicate pages by allowing multiple URLs to display the same content; no matter what the URL or sub sub domain.

how about sub domains? i have a client who insists on using “www” on all their web sites, even if it’s a subdomain. so far, i just recommended using both but after reading your article, i’ll make sure that we are consistent. is there any argument against using http://www.subdomain.domain.com?