How to Resolve the Canonical Issue on Your Website

How to Resolve the Canonical Issue on Your Website

What is the canonical issue?

A canonical issue arises when 301 redirects are not properly in place. This means that your website can be accessed by search engines from several different URLs. This means that search engines can then potentially index your site under different URLs, meaning that it will look like a site of duplicated content.
For example if you have the website http://www.example.com then the index page can be accessed from all of the following URLs:
http://www.example.com
http://www.example.com/index.html
http://example.com
http://example.com/index.html

What can be done to resolve the canonical issue?
The best and most effective way to resolve the canonical issue is with a permanent 301 redirect. This can be implemented in a number of ways, as detailed below. Depending on what server your website is hosted on will determine the method which you use to implement a redirect.
In addition to this it is worth also logging into Google Webmaster Tools and set-up two profiles for your domain; one with the www. prefix and one without. Then go to Site “Configuration> Settings> Preferred Domain” and choose which domain you would like Google to use.
How to implement a 301 redirect with a .htaccess file
If you have your website hosted on any of the below server types then you will be able to use a .htaccess file:
Linux
   Apache
       Zeus
        Sun Java
These are the most common hosting servers and are also the easiest to implement a permanent 301 redirect. Simply copy the code into your existing .htaccess file if you can one or open a blank notepad document and save it as .htaccess
Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^ example.com [NC]
RewriteRule ^(.*)$ http://www.example .com/$1 [L,R=301]

RewriteCond %{REQUEST_URI} ^(.*)//(.*)$
RewriteRule . http://www.example.com%1/%2 [R=301,L]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /(([^/]+/)*)index\.html\ HTTP/
RewriteRule index\.html$ http://www.example.com/%1 [R=301,L]\
You will need to change the example.com domain name to your domain name (all bits highlighted in yellow) and you may also need to change the text highlighted in green. Depending on your site you have a .php index page or it may not be called index, either way check this on your website and change accordingly.
Once the code has been edited and copied into the .htaccess file, save it and upload it to the root of the domain (the same location as the index page). These two pieces of code will redirect anyone who accesses the site to a URL which includes the www. prefix and from the /index.html to the root domain.

Setting up a 301 redirect using Windows server
If you host your website on a Windows server you will need to have administrative access to the hosting server and will need to set-up the 301 redirect through IIS.
Go to “All Programs>Administrative Tools>Internet Information Services”
Navigate to the domain and right click on it, then select “Properties”
Click on the “Home Directory” tab
Select the radial button “A redirection to a URL”
Then enter the URL you want to redirect to (e.g. http://www.example.com)
Click “OK”

This will redirect the domain.

What is a Canonical URL?

Lots of discussion about canonicalization and canonical URLs lately. I’ve discussed URLs and URL structure a few times in the past. We thought that we would help illustrate the idea of canonical URLs. From an SEO point of view here is the definition of a canonical URL:

Canonical URL: the search engine friendly URL that you want the search engines to treat as authoritative. In other words, a canonical URL is the URL that you want visitors to see.

Quite often canonical URLs were used to describe the homepage. The typical example used is that most people treat the following URLs as the same:

www.example.com
example.com
www.example.com/index.html
example.com/home.asp

The fact is that these are all different URLs. From a search engine perspective, this can cause a bit of an issue. Hence the idea of canonicalization. Canonicalization is the process of picking the best URL (to present to the search engines) when there are multiple choices available. Typically a search engine, such as Google will attempt to pick the best URL that they feel is the authority for that page. However, sometimes they may in fact select the wrong one. Now let’s suggest that you have product pages that depending on how the user navigated to the pager returns a different URL… same page but different URL, now we have a duplicate content issue. Not to mention the nightmare for interlinking and external link inventories.

The easiest way to avoid this is to let the Search engines and the users know which is your "preferred URL" a.k.a canonical URL. One suggestion is to redirect all of the variations to your canonical URL (the URL that you want to be the authority). In February, the major search engines announced another solution with the canonical tag. This tag gives you control of the content that you want the engines (and users) to see.

Matt Cutts of Google fame has discussed duplicate content and canonical tags a number of times. One of the questions that he was asked included:

Q: So when you say www vs. non-www, you’re talking about a type of canonicalization. Are there other ways that urls get canonicalized?
A: Yes, there can be a lot, but most people never notice (or need to notice) them. Search engines can do things like keeping or removing trailing slashes, trying to convert urls with upper case to lower case, or removing session IDs from bulletin board or other software (many bulletin board software packages will work fine if you omit the session ID).

We have seen sites that have upwards of 15 versions of the same page but with different URLs. The simplest solution is to have one final destination URL. An easy way to do this is through the canonical tag or by redirecting all of these pages to one authoritative page. The canonical tag is imple to use, all you need to do is add this tag to specify your preferred version of a URL inside the (head) section of the duplicate content URLs.

Canonical simply means relating to or belonging. It also means reduced to the simplest and most significant form. Just remember that a canonical URL is the simplest and most significant (authoritative) version of the URL that you want to be seen.