www and non www can suffer duplicated content

Question

Do you know if i should use canonical tag, or 301 redirection from

http://mydomain.com to http://www.mydomain.com

To avoid duplicated content penalty in case other pages link to the domain without the www.? or is Google enough smart now just to identify whats the canonical one?

Answer 1

If you don't specifically tell Google your preference you will probably have duplicate content issues. There is more then one way to inform Google of your preferred domain:

1. Do a 301 redirect to use the 'www' or no 'www'
2. Specify your preferred domain in Google Webmaster Tools
3. Use canonical URLs (although it isn't typically used in this situation)