Canonicalisation issues

Working as an SEO programmer, it surprises me how many sites do not implement 301 redirects to fix canonicalisation issues.

Canonicalisation is basically a form of duplicate content as Google sees pages such as http://www.example.co.uk and http:// example.co.uk as well as http://www.example.co.uk/index.html and http://www.example.co.uk as separate pages causing duplication.

On an Apache server these are easily fixed using 301 redirects in an htaccess file. However, trying to do the same redirect on an IIS server is a little trickier, as most of the time you need root access to the server to apply filters; however if this is not possible you can apply a scripted version that will redirect the none WWW’s to the WWW version of the site:

< %
If InStr(Request.ServerVariables("SERVER_NAME"),"www") = 0 Then
Response.Status="301 Moved Permanently"
Response.AddHeader "Location","http://www." & Request.ServerVariables("HTTP_HOST")
End if
%>

Unfortunately, to my knowledge, redirecting the index page to the root cannot be implemented if using classic ASP as it causes a infinite loop; it has to be implemented either via c# in .net, or at the server level. If using the redirection script, or server access is not possible, the only option left open to you is to use the newly appreciated canonical tag which is more of a suggestion to Google that an actual command to denote duplicate pages. I will be touching on this again in later posts.

Adam Wood
SEO Programmer