Subdomains vs. Subdirectories

Well, here’s the deal. There are theories all over the place these days about whether you should organize Web sites using sub-domains (e.g. “”) or sub-directories (e.g. “”). WordPress Multi-User forces you to make a choice of one or the other UPON INSTALLATION. No pressure…

I’m setting up a development environment within the domain on a University-owned server. As a result, in order to get the sub-domain functionality going, the network and server administration folks need to get involved, which may constitute more overhead for them in the long run. It’s another line of code to the DNS, but, there are always network implications for things like this. I don’t like doing things that involve having to bring in a multitude of folks to support it, and to respond to what can appear to be idiosncratic requests. So, I feel it’s my duty to research whether or not the bang for the buck of a subdomain structure is worth it.

SEO Consideration

With the acknowledgement of the unfortunate fact that SEO field is more art than science, a moving target, and at any point in time, full of spurious claims, but I digress. There are indeed some ways to help search engines get to your stuff quicker 🙂 Using a subdomain, supposedly, has search engines treat that section as a separate site, with equal importance, or of comparable organizational weight, as the parent site.

Using this rationale, it is easy to see why UMWBlogs uses sub-domains. Blogs by individuals within the domain are of equal weight, and each constitute, essentially, their own web environment, deserving to be crawled as a “root” site unto its own. Interlinking, and crawls between blogs that lead to the “network effect” of the social web, would arise from the individual choices made by the bloggers. If your blog is relevant, it gets linked to, and its ranking goes up because the quality of the content is compelling. So, rather than a top-down measure of your blog’s importance, you have a more organic measure of your blogs relevance. In essence, the information architecture is 3-dimensional and always changing.

With a large-scale university site, this type of status may not apply to each area of content. For instance, I would not consider the Web site for, say, the EagleOne card office (e.g. to be on the same level of importance as the College of Education (e.g., That is because, within an organization, although there are ongoing shifts and reorgs, at any point in time there is a certain fixed and hierarchical relationship between organizational units, and certain areas of information that will always be more important to external audiences requiring predictable, easy pathways. Hard-linking within a directory structure, supplemented by the more organic linking that occurs over time, may be a better way to go in that instance.

But, here’s the rub…

With WPMU, my understanding is that it’s one or the other: Subdomains or subdirectories. Upon installing the app. Sigh…

Ideally, a combination of the two would be best. That is, chunking the site into its major organizational (or content) areas, and then having a sub-directory structure beneath each one. This could, for example, play out as follows:

  • etc.


  • etc.

At this point in time, if we were to set the sub-domains in stone, we may regret it down the road — anyone?

To get to the combination of sub-domain and sub-directory, my understanding is that we’d need a SEPARATE WPMU INSTALL FOR EACH SUB-DOMAIN. Can you spell maintenance headache? (Of course you can — we ARE at a University, afterall).

I found a plug-in that purports to do this:

I’m always hesitant to use a plug-in for what seems to be core application functionality, but, hey, it’s a development environment! Still are there folks out there who have tried this plugin, and what kind of success have you had?


#1 Reverend on 07.17.10 at 11:10 am

OK, let’s think about this. In some ways what you are asking for is a means to do subdomains for larger entities like, but that’s not really a subdomain, because if it were it would be when you created an advising blog—or any other blog under that domain.

The hierarchical point you raise is a good one, and I can see the value of subdirectories following that logic, but the 3 dimensional logic of subdomains also has its attraction. Though, to be honest, the real value and distinction of subdomains really has to do with mapping domains on top of a site/blog. As far as I know, and this may have changed, you can’t map a domain on top of a blog using subdirectories. Now this may not be at all important because domain mapping is really for an individual’s site, like (a mapped domain on umwblogs). If we were thinking about using the space to give faculty and admin their own sites, and provide them the option to map their own domain, then subdomains would be essential. And it would be pretty radical for a university to provide such a slick and cool service on their main domain, and one can ultimately see some value in it. All that said though, UMW Blogs can do that for a faculty, staff or student just as easily, so it may not be key. And if faculty want a professional site on, nothing prevents them from creating and using a provided theme for creating an integrated web presence on the domain.

Now, the plugin you point to is Donncha’s original domain mapping plugin for WPMu, and we are using this on UMW Blogs. It works beautifully, but all it does is lay a site like on top of It simply masks the domain with a new one, it doesn’t provide subdomains on top of a subdirectory structure.

That said, I was thinking about this a bit, and there may be a way to get at the structure you want, namely or, etc. That would require multi-network mapping. In other words, mapping entire networks on top of the existing, but still using the same database and installation (no separate installs, hence no extra maintenance).

Here’s how, on we have several entire networks mapped on the same install. For example, is one network that enables its own subdomains, and is another providing its own subdomains. And whereas is simply one site mapped onto, these other networks can have innumerable sites within them, like this:

So, in theory (and I believe practice), if we keep the WP 3.0 setup as subdirectories, and we create a series of mapped networks (when a WP 3.0 site has enabled multi-sites it is called networks, many networks multi-network—all new terminology for me, so forgive the slippage). And given that mapped networks (versus mapped sites) would be mapped to various subdomains like,, etc., we can actually start thinking of the hierarchical structure along the lines of subdomains for the most important networks—maybe colleges, departments, major administrative offices, etc. So, we can install the whole site as subdirectories, then use the various subdomains we decide upon, etc. as separate networks which will actually create sites within them like

Now, how will this be done? Well, there are a ton of plugins for this, we are using an old one on UMW Blogs, but this one could work just as well:

Or some others we can look at. So, to reiterate, this wouldn’t require a subdomain setup for the multi-site option, we’d use subdirectories, and use the subdomains to map on new networks, like (which is not actually a subdomain install, but a subdirectory install within a subdomain, i.e. The beauty of which is it’s all the same database, user management, directories, etc.

Update: And something else kind cool is that you can control the themes being used on a network by network basis, so each of those multi-networks can have a unique set of theme options for their network. So a particular tweak to education, ELC, etc. See this plugin:

And that brings the whole place of theming and some kind of uber navigation to bring this hierarchy back together in some easily navigable form.

#2 and WP 3.0: Some initial architectural thoughts « bavatuesdays on 07.17.10 at 11:57 am

[…] for getting this conversation started out in the open on her blog The Transparent University. Her latest post focuses on whether our install should be using subdomains or subdirectories, and I recommend you reading it  before going on, because it will contextualize my ideas below […]

#3 Cathy Finn-Derecki on 07.17.10 at 1:06 pm

Jim, many thanks as always. I will finish the install with subdirectories, and go from there.