In one of the test done on my site, I got this error:
Permanent Redirect Not Found
Search engines may think www.mysite.com and mysite.com are two different sites.You should set up a permanent redirect (technically called a "301 redirect") between these sites. Once you do that, you will get full search engine credit for your work on these sites.
what to do if my site is hosted on IIS server…because i didn’t find htaccess file on my server and also my site is built up in ASP .Net…so how to do the permanent redirect…
The reason for doing this is exactly as it says in the error - if your server shows either domain.com or www.domain.com, depending on what you type in or click on, there is a risk that search engines will index both versions of the URL as pages in their own right. That means that any links you have to the pages could be split between the two, and you end up with neither page getting the full benefit of your content and links. Whereas if typing in either version of the URL takes you to the same (preferred) version of it, search engines know that they are just two alternative routes to the same page, so will treat links to either version as links to the same page. This will help your page to achieve its full ranking potential.
This is correct. Either the www version or the no-www version of your site and it’s pages should redirect/resolve to the other.
Since most sites are hosted on Apache webservers, you can you use .htaccess to do this for you. To have the no-www version redirect to the www version use:
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example\\.com$ [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]
Obviously - replace ‘example’ with your domain name.