Do Subdomains Inherit the SEO Authority of the Root Domain?

No. Subdomains do not inherit the SEO authority of the root domain. If you have an existing site and then add a blog to it as a subdomain, the subdomain is going to perform like a brand new website and initially perform poorly in the search engines.

Confusing this question with “Are Subdomains Good for SEO?”

Subdomains are just fine for SEO. You just have to treat them like they’re a second website. If your main website is widgets.com and you have a separate blog.widgets.com subdomain, they’re essentially two different sites. This is a fact. I link out to case studies in my 2014 article Subdomain VS Subfolder. So, yes, a subdomain can rank just as well as a domain. But, if you already have a powerful website and add a subdomain to it, expect to be extremely disappointed when you begin adding content to it that nobody is going to see in organic search.

So, technically, there is absolutely nothing wrong with having a subdomain. If you’re starting a business from scratch and feel like putting in effort to rank two websites instead of one, be my guest.

The misconception.

Search engines treat subdomains no differently than a regular domain. Google has stated this multiple times.

The problem is engineer’s communication skills.
Having worked in IT for 20yrs and employed many engineers I can tell you that if you ask an engineer a question you’ll get an answer which basically makes you want to stick a fork in your eye. Every time people ask Google if subdomains are good for SEO they say something like “Well, kind of, it doesn’t matter if your content is on a subdomain or a subfolder”…

99.999% of the time when people ask “are subdomains good for SEO?” they want to know if subdomains inherit the SEO authority of the root domain. They do not.

Google just answered this most recently in May 2018 in the most confusing method ever. It’s no wonder that people are still wondering if subdomains get “juice” from the main site. I mean, they may get some, but not much.

Here’s a video from Google which has absolutely nothing whatsoever to do with subdomains inheriting a root domain’s authority:

Subdomains are great for:

With my IT background I look at many things on the Internet with a… well… “network” point of view. If you have a portion of your network dedicated to something in particular it’s called a subnet. A subnet is basically a separate but identifiable part of an organization’s network. I look at domains the same way. A subdomain can be an identifiable part of your company but separate. Think Craigslist: raleigh.craigslist.com, for example.

Below are some reasons why you may want to use a subdomain:

  • Promotions
  • Blogs (if you’re aware of the above)
  • Forums (You can not control user generated content)
  • Archived content
  • Thin content you want moved off of your main domain
  • No other option. Sometimes you have a CMS which isn’t WordPress and have no other option.
  • Completely different content. Google does this with maps.google.com which is quite different than google.com
  • Regional sites

And in the “maybe” category, a couple of examples are:

  • eCommerce sites (store.website.com)
  • Franchise sites
  • Multilingual sites
  • Product sites for brands

Recap

Yes, search engines understand that a subdomain is somehow associated with a regular domain, but sticking a subdomain on an existing website which already ranks well will not automatically make the subdomain powerful.

Google does indeed treat subdomains the same as a regular domain as they crawl and index them just like any other site, however the SEO value from the main site is not inherited by the subdomain.

When I think of “content marketing” I think links & content. Hopefully my content can generate natural links or I can discover a away to link to it. Links make a website more powerful. If the site getting the links is a subdomain, it isn’t going to help the ranking of my main site. If the site in question is a business website, I’d avoid the subdomain at all costs because getting links to a business is hard enough as it is. If the site in question is a company site, use company.com/blog/ rather than blog.company.com.

Len

President at Telapost
I create content and do SEO for law firms, small businesses and companies worldwide. I have been generating traffic online since 1992. I have owned multiple successful companies. I'm an organic eater, nature lover and German Shepherd owner. Feel free to contact me here.

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