Subdirectories vs. Subdomains for 2019 and Beyond

Evan Hall - Portent SEO

The one topic I’ve seen Google and SEOs disagree on the most is where the best place to host content is. SEOs say subdomains aren’t optimal, and Google says it doesn’t matter because they can read and understand your content wherever it is. Google even put out a video to try to clarify the matter, but no one was satisfied with their answer.

So what’s the disconnect? While it’s true Google has no problem understanding content on subdomains, SEOs say that content doesn’t perform as well in Google’s search engine. Google disagrees and says that subdomains aren’t a problem, yet the SEO industry continues to publish case study after case study that refutes Google’s claim.

Until Google offers an alternative explanation of what the SEO world is seeing, marketers still have to decide how to host their content.

As an SEO, my recommendation is to host your content on your primary domain – unless you have a very good reason not to. Even if Google turns out to be correct, and it doesn’t matter either way for performance, organizing your content in subdirectories on your primary domain is the better decision for your infrastructure and long-term SEO.

It’s a Technical Difference

Example of URL best practices for SEO

 

The difference between placing a blog at blog.brand.com or brand.com/blog seems insignificant. We’re putting blog at the end of the URL instead of the beginning, right?

The distinction goes back to the early days of the internet before the web existed. It was conventional for system administrators to host additional services on subdomains, like mail.domain.com for the email server, or ftp.domain.com to filesystem access.

For the web to come into being, servers needed to be able to deliver HTML files to remote users, so system administrators added web servers to the network and made them available from the www subdomain. That’s why everyone’s URL is www.brand.com. So you’re probably hosting your content on a subdomain already, but it’s your primary subdomain.

What this blog explores is whether you should put things like your blog or international content on subdomains other than your primary.

The Results are In

SEO’s aren’t wrong to believe subdirectories work better for organic rankings. There are several published examples of brands moving their content to their primary domain and seeing performance boosts. Rand Fishkin was gracious enough to compile a list of case studies that document this effect.

The examples in Rand’s list that make the case most clearly are here:

There’s even an example of a brand moving their blog to a subdomain and seeing a performance drop.

Would you see a similar effect if you moved your blog from blog.brand.com to brand.com/blog? Hard to say. Every case is different, and migrating content is rarely the only change being made in these examples.

Keep Your Link Authority in One Place

The case against subdomains is not just about immediate rankings; it’s also about guiding your SEO strategy into the future. This is the main reason why I recommend keeping content on the primary domain whenever possible.

Where would you rather host your content, on two domains with 1,000 backlinks each, or one domain with 2,000 backlinks?

These are the possible futures you’re choosing between when considering using a subdomain for your content. Over the years, your content is going to earn backlinks from all over the web. If your content is in a separate location, like a blog subdomain, you’re splitting your backlinks between the two.

Suppose five years down the line your website is redesigned, and you retire the subdomain and switch to a subdirectory structure for your blog. You’ll be in a situation where you have to redirect all those links from the subdomain to the primary domain, and as we know, redirects waste link authority.

Having to redirect a lot of backlinks is not a great position to be in. You would have been better off if those links pointed to the primary domain in the first place.

Keep Your Overhead Low

How many websites do you want to pay for? How many web applications do you want your engineers to maintain? Every subdomain you add to your website introduces another hosting environment to your technology stack and all the business concerns that come with it.

A new subdomain could mean additional costs for any of these:

  • 3rd party hosting or subscription fees
  • Additional SSL certificates or a wildcard certificate
  • Developer hours for the subdomain CMS
  • Additional colocation space or network hardware

You would also have to manage login credentials, analytics, security, and webmaster consoles for the subdomain. If you have regulatory compliance to worry about, these headaches add up fast.

Plan Ahead

The best way to avoid having to deal with the subdomain question at all is starting with a website that does everything you want. Very often, I’ll find brands that try to tack on functionality later due to lack of foresight.

Begin with an infrastructure that will do everything you need. If you’re going to need a blog or eCommerce experience, choose a CMS with those built into the app. Or you could even go with an extensible CMS, like WordPress or Drupal. Shopify has a lot of SEO quirks, but it’s relatively solid and comes with a few site speed improvements out of the box.

Planning ahead also includes anything you’re going to test for your digital strategy. If you’re considering trying out blogging, and I recommend you do if you aren’t, plan how you’re going to proceed after a successful test. You will need to find a way to add a blog to the main domain if the content strategy test works (and it probably will.)

Sometimes a Subdomain is the Right Choice

There are a few cases where a subdomain makes the most sense for your brand outside of technical necessity. Usually, it’s for a sub-brand or a product that is substantially different than what the brand normally sells.

If your content satisfies most of these criteria, then you should probably use a subdomain:

    • The content or branding isn’t different enough to justify an entirely different domain
    • Users would be confused if they navigated between the two content experiences
    • The content sells a completely independent product or is part of a portfolio of products

Google itself is pretty good at this. They have developers.google.com, assistant.google.com, cloud.google.com, store.google.com… and the list goes on. Each subdomain is an aspect of Google, but totally independent and hosts its own thing.

Another valid case for a subdomain is content that will never need to be indexed by a search engine. Paid landing pages, content behind login screens, and company intranets are all good examples.

Mobile and International Considerations

I’ve seen a lot of brands create trouble for themselves by adopting subdomains for mobile and international versions of their websites. They’re the worst option for either strategy and create a lot of headache for your SEO team down the line.

The future of the web is responsive and mobile-first. It’s the easiest and simplest way to adapt to modern internet usage. Brands that disregard this tend to tack on mobile subdomains that plague their technical teams with problems like:

      • Wasted crawl budget and canonicalization issues
      • Server-side device detection and redirect handling
      • Maintaining content parity between mobile and desktop sites
      • Shrinking content and navigation to fit mobile screens

International websites are usually implemented in three ways: ccTLDs, subdirectories, and subdomains. Subdirectories have no upsides over the other two options. ccTLDS aren’t optimal either, but at least they contain a strong signal about which country they’re targeting.

Using a subdirectory strategy for international websites is something I see more brands using every year. I think they are realizing the benefits of having everything in one place: one CMS, one development team, better content parity, and easier management of hreflang tags.

Imagine using a subdomain strategy for your blog, mobile site, and international content. Your URLs would look like this: m.fr.blog.brand.com. What a mess.

The Dispute Will Rage On

Correct me if I’m wrong, but I don’t think anyone in the SEO industry has proven the technical reason why subdomains tend to perform worse than subdirectories. I have my suspicions, but nothing that’s easily tested. Google definitely isn’t going to come forward with the mechanism; they never talk about how their systems actually work.

Like Google’s 200+ secret herbs and spices, we’ll never really know for sure.

Unless there is a new wave of case studies concluding that switching to a subdirectory strategy destroyed their rankings or nothing happened, it’s a safe bet to switch to a subdirectory.

Evan Hall - Portent SEO

Evan Hall

SEO Strategist
SEO Strategist

Evan is an SEO strategist with nearly a decade of experience in digital marketing, including web analytics and split testing. He loves solving technical SEO problems and is currently learning JavaScript and Python. When not taking the SEO world by storm, Evan enjoys table-top games and reading science fiction.

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