Most site/business owners know enough about SEO to get by. They know that they need an organized site structure. They know that they need optimized meta tags. They know that they need content that is relevant to competitive search queries. And they know that canonicalization can help them avoid unwarranted competition among pages from their own site.
These items listed above are common problem areas found during the optimization process. Each of these problems can be fixed with a few changes to your site, and since you own the site, you can address these problems at your leisure.
Unfortunately, canonicalization is no longer only an onsite problem. Sites, which do not properly establish a canonical URL for a particular page, can cause unwarranted problems for your site if the page in question has links to your site embedded in the content. Just as a reminder, canonicalization refers to a single web page that can be loaded by multiple URLs. Google will read each of these URLs as separate pages. For example,
All of the above would point to the same page, but search engines read these as separate pages.
Normally this is an onsite problem that has similar consequences to duplicate content; however this can cause problems to your backlink profile if a single piece of content with links to your site is duplicated through different URLs. Since the Panda and Penguin updates, Google has been cracking down on links that smell unnatural. The Google Webmaster Central blog identified some examples: widgetbait, paid links, blog spam, guestbook spam, excessive article directory submissions, excessive link exchanges, other types of linkspam, etc.
The Ramification of the Canonicalization of Backlinks
A natural backlink profile is bound to have some backlinks that come from sites that don’t establish canonical URLs for all of its pages. Even if you do have some of these links pointing to your site, Google and other search engines are far more likely to simply devalue the link juice coming from the duplicated pages and content rather than throw the hammer-strokes that came down from the Panda and Penguin updates.
The problems begin when a large portion of your backlink profile comes from canonical backlinks or duplicated content. You can begin to identify which domains are publishing canonical backlinks to your site with the help of Google Webmaster Tools, which provides a list of domains that are linking to site. This data includes the domains that link to your site, the number of links to your site from those domains, and the number pages that the domains are linking to. Now, if example.com has 200 links to your site but only links to two of your pages, then that ratio of links to pages should throw up a red flag. There is a possibility that example.com is creating duplicate content through canonicalization that has links to your site. For instance, let’s say that example.com is a news site that published an article that has a link to your site. There could be multiple URLs created that point to the same page:
In the case above, there are three links to your site, but those links are only pointing to the same, one page. That means a single link could have exponentially unnatural link juice value.
News sites and blogs are notorious for creating duplicate content. That is why Google came down so hard on blog spam. So if your backlink profile has a decent chunk of links from sites with canonicalization issues, then you need to respond to this problem.
Diversify your Link Development
Links from high traffic blogs and news sites are not going to hurt you, but a large number of canonical links could do some damage. So, work on building links on pages that are not so easily reproduces on multiple URLs. Join a professional organization like the local chamber of commerce. Sponsor an event or non-profit organization. Present at a conference relevant to your business. Look for opportunities to get listed on resources/informational lists. These all would create quality and stable backlinks.
The Tool of No Return
If you have a chronic problem of a low quality domain that has a high number of links only pointing to one or two of your pages, then you can ask Google’s Link Disavow Tool to ignore all links from that domain. This should only be done when the domain in question has clearly been shown to use spamming practices. Asking Google to delete a domain could have negative consequences on your rankings if that domain carried quality links to your site. So this is the last resort. You would benefit more from time spent on diversifying your link profile rather than unsurely disavowing domains.
If you are having problems gaining traction with your link building even if you are adding quality links month to month, then this may be a problem worth looking into. Don’t panic if you see the first possible sign of canonical backlinks. Monitor your backlinks and your rankings and see if the problem persists over time. If there is a problem, your next step should be to change the way you acquire links to add more diversity into your profile. Positive link building will do more good that asking Google to ignore an entire domain.