Google Webmaster Tools announced in December 2009 that it will from now on support what is known as the cross-domain rel=”canonical” link. This is big news for people who have legitimate reasons for duplicate content across domains. The main reason for duplicate content across domains is that a website is moving to a new URL.

You can see an example of the use of rel=”canonical” in the first screen shot, taken from Google’s Matt Cutts’ blog.

The reason this is important is that search engines confronted with duplicate content will take one version and filter out the other versions. Therefore if your site is moving to a new URL, it is possible that the wrong site will get indexed, which you definitely don’t want.

The best way to avoid the indexing problems that come along with cross-domain content duplication is to use use what are called 301 redirects. 301 status means a page has moved permanently to a new URL. An example of the use of this code can be seen in the second screen shot, which came from http://www.webweaver.nu/html-tips/web-redirection.shtml.

The two pages do not have to be totally identical. According to Google, slight differences in content will be ignored. If you are just switching servers, however, you should be able to port your URL with you making a redirect unnecessary. But if you’ve got a hot new URL, you’ll want to do either a 301 redirect or a rel=”canonical” redirect.

This entry was posted on Monday, January 25th, 2010 at 5:31 am and is filed under Google, Web Design. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.