I notice some websites use "www" while others don't. From what I understand, using BOTH for your website may cause duplicate content issues with search engines. To give an example, I notice The National Portal of India currently uses http://www.india.gov.in/ and http://india.gov.in/. How important is it for them set up a redirect from url without www to url with www (or vice versa)? Are they likely to suffer from duplicate content if they don't see up a redirect?

Please share your thoughts so that we can all learn!