Subdomain cannibalization

[Mat_C]

Hi,

I am doing the SEO for a webshop, which has a lot of linking and related websites on the same root domain. So the structure is for example:

Root domain: example.com
Shop: shop.example.com
Linking websites to shop: courses.example.com, software.example.com,...

Do I have to check which keywords these linking websites are already ranking for and choose other keywords for my category and product pages on the webshop? The problem with this could be that the main keywords for the category pages on the webshop are mainly the same as for the other subdomains.

The intention is that some people immediately come to the webshop instead of going first to the linking websites and then to the webshop.

Thanks.

[Everett]

The short answer to your question is: Yes, you should know what keywords each of your subdomains rank for and should adjust strategy accordingly.

The long answer is that I want to see this website because it doesn't sound like something I'd recommend doing in the first place. It used to be that subdomains were treated completely differently from the parent domain and you could, theoretically, take up the entire first page of results with your subdomains. Content mills like About.com took this to the extreme and Google responded so you don't tend to see that happen much anymore. As I understand it, Google also attempts to make a determination as to whether this is the same "site" or multiple, unrelated sites, such as site.blogspot.com subdomains and treats them accordingly.

These days, the general consensus is that you should be using subdirectories/folders instead of subdomains for a variety of reasons, unless the subdomain is for a different site, or something you don't really need to have indexed, like a closed app.

[Everett]

Also, don't forget to use Google Search Console's "Property Set" feature. However, I think they're about to start auto-created property sets by aggregating subdomains soon anyway: https://www.seroundtable.com/google-search-console-domain-property-26645.html

[Mat_C]

Thanks for your answer Everett.

The structure was indeed created some years ago, when ranking with different subdomains wasn't really a problem. It is quite normal that there is an overlap between the webshop subdomain and other subdomains. The subdomains dive deeper into a specific part of the business (tax, legal, formations,...) but on the webshop all of these different products from the subdomains are sold.

However, for some search terms, some of the subdomains all rank on the first page. For example: https://www.google.com/search?q=successierekenaar&oq=successierekenaar&aqs=chrome.0.69i59j0.3257j0j7&sourceid=chrome&ie=UTF-8
As you can see, the root domain as well as two subdomains and a link to an app, take the first four positions in the SERP.

Key question is: if there is a possible search term to rank for, but one of the subdomains already ranks for this term, can it still be used? Otherwise, it won't be easy to find a unique search term with a high enough search volume for each product, since it is a market with very specific products.
On the other hand, if subdirectories were used, it basically comes down to the same: never try to rank two pages for the same search term.

[Everett]

Hello Mat,

I don't think I'm seeing the same SERPs as you. Is there any way you could give me an example of one of these subdomains?

And yes, you're absolutely right that the same problem of keyword cannibalization would apply to subdirectories as well.

If it's the woltersk....lu domain I am getting non-secure warnings from Firefox when I try to access it.

How many different subdomains are there / will there be? Is it just shop.domain.lu and www.domain.lu or are there others? I didn't see any for "courses." or "software." in the SERP example you provided with the link. If it's just one, I think that's manageable. For example, maybe www. could focus on informational queries (e.g. JavaScript course) and shop. could focus on transactional ones (e.g. Buy Acme JavaScript course). Maybe one could focus on reviews and comparisons, or long-tail queries while the other focuses on short-tail queries. Without knowing more about the domains and your business, it is difficult for me to say.  If you have three or four subdomains all going after the same keywords, that's definitely a problem and I don't think you can avoid cannibalization. At that point, it would be best to choose the strongest domain/subdomain and focus your efforts on ranking one of them instead of watering down your efforts over several.