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.