There are multiple reasons to redirect URLs. For one, your web pages may have moved but their old URLs may still live in users’ bookmarks or in search engine indexes. Without implementing some sort or redirection, that traffic would be lost to a 404 Error Page.

301 redirect is the most efficient and Search Engine Friendly method for webpage redirection. It’s not that hard to implement and it should preserve your search engine rankings for that particular page. If you have to change file names or move pages around, it’s the safest option. The code “301″ is interpreted as “moved permanently”.

Check Google Guidelines about specifying preferred domain – http://www.google.com/webmasters/checklist/

To Google, http://example.com and http://www.example.com are completely different sites and can display completely different content.

Better understanding of www vs non-www from a SEO Standpoint:

· In most cases non-www and www return to same website, in other words, a duplication of entire site.

· In order to maximize pagerank and the effectiveness of SEO campaigns, we should ensure there is no duplicate content on site.(This is where both the www and non-www versions of web pages are listed in a search engine. This is said to possibly trigger a duplicate content penalty and/or split page rank. )

· Many search engines have filters in place to remove the duplicate listings – this keeps their search results clean, and is overall a good feature. We can avoid potential problems (and get a better view of web data) by specifying preferred domain.

· The popularity of link is split between the two URLS, decreasing the value of each link and subsequently web site content.

I will suggest you to implement 301 redirect on the site without the ‘www.’ to make the site permanently redirect to your ‘www.’ domain. Search Engines will know to ignore the non-www and use the www instead. (Google is only showing the www version.)

Below are a Couple of methods to implement URL Redirection:

1. IIS Redirect

· In internet services manager, right click on the file or folder you wish to redirect

· Select the radio titled “a redirection to a URL”.

· Enter the redirection page

· Check “The exact url entered above” and the “A permanent redirection for this resource”

· Click on ‘Apply’

2. ColdFusion Redirect

<.cfheader statuscode=”301″ statustext=”Moved permanently”>
<.cfheader name=”Location” value=”http://www.new-url.com”>

3. PHP Redirect

<?
Header( “HTTP/1.1 301 Moved Permanently” );
Header( “Location: http://www.new-url.com” );
?>

4. ASP Redirect

<%@ Language=VBScript %>
<%
Response.Status=”301 Moved Permanently”
Response.AddHeader “Location”,”http://www.new-url.com/”
%>

5. ASP .NET Redirect

<script runat=”server”>
private void Page_Load(object sender, System.EventArgs e)
{
Response.Status = “301 Moved Permanently”;
Response.AddHeader(“Location”,”http://www.new-url.com”);
}
</script>

6. JSP (Java) Redirect

<%
response.setStatus(301);
response.setHeader( “Location”, “http://www.new-url.com/” );
response.setHeader( “Connection”, “close” );
%>

7. CGI PERL Redirect

$q = new CGI;
print $q->redirect(“http://www.new-url.com/”);

8. Ruby on Rails Redirect

def old_action
headers["Status"] = “301 Moved Permanently”
redirect_to “http://www.new-url.com/”
end

9. Redirect Old domain to New domain (htaccess redirect)

Create a .htaccess file with the below code, it will ensure that all your directories and pages of your old domain will get correctly redirected to your new domain.
The .htaccess file needs to be placed in the root directory of your old website (i.e the same directory where your index file is placed)

Options +FollowSymLinks
RewriteEngine on
RewriteRule (.*) http://www.newdomain.com/$1 [R=301,L]

Please REPLACE www.newdomain.com in the above code with your actual domain name.

In addition to the redirect I would suggest that you contact every backlinking site to modify their backlink to point to your new website.

Note* This .htaccess method of redirection works ONLY on Linux servers having the Apache Mod-Rewrite moduled enabled.

Redirect to www (htaccess redirect)

Create a .htaccess file with the below code, it will ensure that all requests coming in to domain.com will get redirected to www.domain.com
The .htaccess file needs to be placed in the root directory of your old website (i.e the same directory where your index file is placed)

Options +FollowSymlinks
RewriteEngine on
rewritecond %{http_host} ^domain.com [nc]
rewriterule ^(.*)$ http://www.domain.com/$1 [r=301,nc]

Please REPLACE domain.com and www.newdomain.com with your actual domain name.

Note* This .htaccess method of redirection works ONLY on Linux servers having the Apache Mod-Rewrite moduled enabled.