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Domain canonicalization

Medium Influence Hard to implement

When the same content is offered under different URLs it can be considered duplicate content. In order to avoid possible penalties and to concentrate your visitor numbers and PageRank to one website, you should canonicalize your domain.

Decide which URL you want to use primary and configure a redirect from the domains with duplicate content to your main domain.

There are several different reasons, why it can be useful to be reachable under different URLs. When you registered a domain (e.g. ‘www.acebit.com’), but want to be found under different URLs as well, e.g:


In this case you should canonicalize your domains and add a redirect to your main domain www.acebit.com. This way you avoid duplicate content and concentrate your PageRank on one website.

A 301 redirect is a HTTP status code replying that the content was moved permanently to another URL and redirecting the visitor to that URL. This kind of redirect is configured in the HTACCESS on a Apache server.

Redirects can also be done by using the <link> tag with the rel="canonical" attribute. This tag needs to be entered in the <head>.

e.g.: <link rel="canonical" href="http://www.acebit.com"> where www.acebit.com is the main domain, where the visitor should be redirected to.

Helpful Links

Google Webmaster Help: Use canonical URLs

GoogleWebmasters: 301 vs rel=canonical: