Your web pages may have moved but their old URLs may still live in users’ bookmarks or in search engine indexes. So, you must redirect that URL to your new domain. It is a good practice to have redirects (e.g. for example, from your non-www version of your site to your www version or vice versa). There are several ways to redirect domains. The search engine friendly way to redirect URLs is to use what is known as a 301 redirect.
301 Redirection – This is the most SEO Friendly redirection. This is actually a function of the web server that redirects a visitor from the current page to the new page and returns a response code that says that the original page has been permanently moved to the new location. Search engines identify this redirection very easily and credit the new URL with all the back links and PageRank of the old URL. This type of redirection is expected to have the least impact on the search rankings.
To ‘301 redirect’ an old URL to a new one, just go to your web host’s control panel, and choose the “Redirects” option. You can then set up the redirect by filling the blanks. You want to choose redirect option “Permanent” to implement a 301 redirect. To 301 redirect an additional domain (like in the case of the .net or the .org version of your domain name), you have to set it up as an add-on domain with your web host.