Configuring a Blog for SEO: Subdomain vs. Subdirectory
In “Your Blog Is Key to Search Engine Optimization,” I explained that blogs are an important strategy for SEO. But there are a number of variables that affect just how effective it can be at enhancing your site’s rankings. If you’re just now incorporating a blog, the first question is whether to implement it on a subdirectory URL of your existing site or whether to put it on its own subdomain. The answer to which is better depends on a number of factors. So read on to understand what might be the best direction for you.
For many webmasters, it may be easier to contemplate setting up new content for a site in a newly named subdirectory. For example, many sites choose to place their blog in a subdirectory that’s aptly-named “blog,” as in:
This can be easier to do in cases where a webmasters don’t have full control or confidence in customizing their DNS — domain name system. However, there are often instances where a site’s primary domain is hosted on a platform that is restrictive in terms of what types of software may be implemented on it. This can result in webmasters considering a blog hosting solution that is more separate and distinct from their primary sites. If a legacy content management system on the main server or security rules create an impediment to installing the blog software on the site, webmasters often end up setting up a completely new domain for the blog, or use a subdomain of their main site, as in:
In most cases, setting up a completely new domain name is not advisable. A new domain has some disadvantages in terms of needing to rapidly achieve sufficient numbers of inbound links to gain traction with Google. Without aggressive link development, a new site will be subject to the “Sandbox Effect,” whereby Google penalizes a site for an artificial use of inbound links. But without the links it can take months and even years to achieve the necessary trust to rank appropriately. Not to mention, link building requires sophistication — see “How Not To Build Links for SEO,” my previous article — or else it will cause serious problems.
Since part of the reason for a blog is to introduce content that will be a virtual magnet for natural links, it defeats the purpose if you have to hotwire a whole new domain with links to launch it. So, for most sites a completely new, standalone blog domain is a nonstarter.
Three or four years ago, I would have recommended using the subdomain approach as having a bit of an edge in the algorithms. Back then, subdomains for blogs and other types of content sections on sites appeared to convey some advantage because the search engines tended to treat the links from the subdomains to your main domain very favorably — as though they were good external links. And, they treated the subdomain similar to external sites, while sidestepping the Sandbox Effect.
Subdomains in Search Results
Search engines also used to list each of your subdomains in the search results as completely separate sites, giving you the opportunity to dominate even more of the same keyword search result page — your various subdomains could be listed one after another, taking up multiple slots on the same page.
However, search engines, and Google in particular, began clustering a site’s subdomains together when making ranking determinations and in choosing (limiting) how many pages from a particular site would display on the same results page. Essentially, Google treats a site’s subdomain pages identically to subdirectory pages in many circumstances. (Google’s Matt Cutts recently reiterated this guidance once again.)
As search engines became more sophisticated at associating subdomains with a primary domain, the advantage of one approach over another became very marginal. PageRank via links from subdomain pages seems to convey no greater weight than from pages within subdirectories now, and the number of links from the same domain allowed to display on a search results page has become constrained and limited.
Even though the differences have become more marginal, there are still factors that may make one approach more optimal.
Social media signals and the sites from which they originate are becoming more influential as search ranking signals. The signals from these sites are relatively new and rapidly evolving. As such, there’s some advantage to be had from avoiding subdomains and going with subdirectories. Services like Twitter and Facebook are now making evaluations as to the popularity of status updates and links included within them – and they are newer at associating related URLs together. Link shortening services used in relation to multiple different social media sites like Bit.ly are also newer at evaluating related links.
Since these resources are newer at handling links, they don’t always associate links from domain variations together. Yet, their evaluations of relative popularity are being used by search engines to influence rankings. (It’s even possible that the search engines do not associate site signals originating from social media sources in the same ways as link evaluations are done from static web pages, although this possibility seems less likely.) Because of this factor, there may now be more advantage for hosting blogs on the same domain, but under a subdirectory.
There’s another complex factor to weigh before settling on the subdirectory approach. Most of Google’s attention to rolling up subdirectory URLs is focused upon its main keyword search results. The algorithms for their other specialized, vertical search engines operate a little differently. Google doesn’t handle subdomains in the same way in Images Search, Video Search, and Local Search. A good case in point is how it handles Craigslist.org or OLX.com – classifieds sites that operate numerous subdomains with photos appearing from each of them. In Google’s Images Search for various keywords, images from multiple subdomains from those sites can appear in the search results simultaneously. For example, a search for “appliances for sale” shows pictures from multiple OLX.com subdomains:
With different media and different display needs for user experience, Google doesn’t apply the same restrictions that are applied with regular keyword results pages.
So, I’d apply the following guidelines when deciding whether to go subdirectory versus subdomain for your blog.
- Don’t change what you have. If you already have a blog on one or the other format, you probably shouldn’t worry about moving it. Google treats both approaches very similarly overall, and changing all of your URLs will often result in much more serious problems that will negatively impact your rankings.
- Lean towards a subdirectory. In most cases, there may be an advantage for going with the subdirectory approach. There’s no longer the same pseudo-external linking advantage that we’ve sometimes seen in the past, and the growing influence of social media signals may convey greater preference for using your primary domain name. As you get more and more social media “buzz” over time — assuming you’re consistently posting content on social media and interacting with your audience — using a single domain helps all that signal to get associated with one domain rather than getting spread across multiple ones.
- Use a subdomain in certain cases. Use a subdomain if your primary domain is configured in such a way as to make it highly difficult to add necessary blogging software — I recommend WordPress, as it is most search engine friendly — and it would be too time-consuming and costly to reconfigure your server to accommodate the blog. However, there’s still another option in this case: You can set up a subdirectory on your primary site’s server and reverse proxy it over to a separate server where you have installed the blogging software. Using this method, your blog URL configuration really should not be dependent upon whether you’re still running inflexible legacy software.
- Subdirectory for images and videos. If you’re planning on posting many images or videos on your blog over time, that may create an exclusion case for going with subdirectories. If you will be posting many images and videos and you have some similar content on your primary domain and other subdomains, it might be more advantageous to use the subdomain approach to expand your chances of visibility in the vertical search results.
My guidance in the past would have been different, but today there seems to be advantage in most cases to go the subdirectory route. There may even be greater advantages to this over a longer period of time, since you’re steadily developing the prominence of your primary site, and it could be easier to maintain your legacy URLs without spreading them across multiple subdomains. There are still instances where it can make sense to choose a subdirectory approach instead, but the majority of sites do not fall into those exception cases. Either way you go, Google and other search engines can handle your postings, and blogging steadily over time will convey advantages to your site with either approach.