Setting the preferred domain

Based on your input, we've recently made a few changes to the preferred domain feature of webmaster tools. And since you've had some questions about this feature, we'd like to answer them.

The preferred domain feature enables you to tell us if you'd like URLs from your site crawled and indexed using the www version of the domain (http://www.example.com) or the non-www version of the domain (http://example.com). When we initially launched this, we added the non-preferred version to your account when you specified a preference so that you could see any information associated with the non-preferred version. But many of you found that confusing, so we've made the following changes:

• When you set the preferred domain, we no longer will add the non-preferred version to your account.
• If you had previously added the non-preferred version to your account, you'll still see it listed there, but you won't be able to add a Sitemap for the non-preferred version.
• If you have already set the preferred domain and we had added the non-preferred version to your account, we'll be removing that non-preferred version from your account over the next few days.

Note that if you would like to see any information we have about the non-preferred version, you can always add it to your account.

Here are some questions we've had about this preferred domain feature, and our replies.

Once I've set my preferred domain, how long will it take before I see changes?
The time frame depends on many factors (such as how often your site is crawled and how many pages are indexed with the non-preferred version). You should start to see changes in the few weeks after you set your preferred domain.

Is the preferred domain feature a filter or a redirect? Does it simply cause the search results to display on the URLs that are in the version I prefer?
The preferred domain feature is not a filter. When you set a preference, we:

• Consider all links that point to the site (whether those links use the www version or the non-www version) to be pointing at the version you prefer. This helps us more accurately determine PageRank for your pages.
• Once we know that both versions of a URL point to the same page, we try to select the preferred version for future crawls.
• Index pages of your site using the version you prefer. If some pages of your site are indexed using the www version and other pages are indexed using the non-www version, then over time, you should see a shift to the preference you've set.
  

If I use a 301 redirect on my site to point the www and non-www versions to the same version, do I still need to use this feature?
You don't have to use it, as we can follow the redirects. However, you still can benefit from using this feature in two ways: we can more easily consolidate links to your site and over time, we'll direct our crawl to the preferred version of your pages.

If I use this feature, should I still use a 301 redirect on my site?
You don't need to use it for Googlebot, but you should still use the 301 redirect, if it's available. This will help visitors and other search engines. Of course, make sure that you point to the same URL with the preferred domain feature and the 301 redirect.

You can find more about this in our webmaster help center.