Friday, February 20, 2009

Dynamic Websites - Promote a Single Permalink URL

Website may allow for multiple URLs to retrieve the exact same content. A common example is:

Which might also be found as:

Notice that the only difference between the above URLs is the addition of website traffic tracking parameters and sorting parameters. There are also more complicated examples such as sub-folders and alternative page extensions.

These duplicate URLs, if indexed by the search engines, will dilute the ranking value of your website pages. To prevent multiple versions of the same page from being separately indexed; the big 3 search engines now support a header link to reference the primary URL:
<link rel="canonical" href=""/>

Search engines and their crawlers will interpret that directive in allowing the primary page to take precedence as well they will likely attribute page ranking factors to the appropriate page.

This should be applied to all dynamic pages (ASP, PHP, etc) as a
general publishing practice since most of these pages commonly support query string parameters for sorting and tracking and 301 redirecting usually isn’t practical.

For more information see:
Google - Specify your canonical
Yahoo - Fighting Duplication: Adding more arrows to your quiver
Microsoft - Partnering to help solve duplicate content issues - Google, Yahoo, Microsoft unite…

David Rodecker
Founder & CTO
getting local business online