Will a subdomain influence our SEO?

SEO factors for domains, subdomains and directories

Published by OSG Team03.09.2020 Category: SEO

[email protected] / Brian A. Jackson

The domain plays an important role in search engine optimization. We will show you what you need to pay particular attention to from an SEO point of view with subdomains and subdirectories and what you should use to structure your website.

Introduction to domains

Each domain is assigned an IP address so that it can be clearly identified on the Internet. The IP address consists of four octets and results in a certain number combination (e.g. 123.343.55.666). Since it is difficult to remember such a combination of numbers, every IP address is assigned to one DNS (Domain Name System) Assigned to a server, which in turn converts the combination of numbers into a domain name when requested.

Structure of a domain

Every domain name consists of several parts, which are also called “levels” and are separated by dots. The full name of a domain is saved as a FQDN (Fully Qualified Domain Name).

The different levels

  • First level (Top Level Domain; .TLD)
    The domain ending is often chosen according to country, for example .de for Germany, .ch for Switzerland, .at for Austria. The ending .com is often used for international sites. With the search engines, the country-specific domains usually prevail, so in the German Google search mainly .de pages are listed in the first places. With the Webmaster-Tools product from Google, a non-country-specific TLD can be assigned to a geographical target, which can work against the country-specific TLDs at least a little.
  • Second level domain
    Here the internet presence gets a description left to the creativity of the domain owner. If possible, the name should be chosen so that visitors can already read here which products and / or services are offered.
  • Third level (third level domain or subdomain)
    If you own a domain, you can create as many subdomains as you want and offer different content on each one.

What is a subdomain?

Subdomains are used to logically separate the different services and offers within their own domain. For example, mail.musterseite.de is used for the mail server and is therefore a subdomain of the musterseite.de domain.

Furthermore, one can e.g. different country pages specify as subdomains of a top side, this would then be structured as follows:

  • de.musterseite.com
  • at.musterseite.com
  • ch.musterseite.com

or you can integrate the blog as a subdomain: “blog.musterseite.com”.

Important SEO factors for subdomains

Just thematically different areas should be outsourced to a subdomain
(These can act as replacements for sub-folders and are more easily hosted on a proxy server.)

Part of the domain strength gained is passed on to subdomains, but the transfer rate is not as high as with sub-folders within the domain.
In order to achieve a good result in the SERPs, the subdomains should also have a own link building structure receive.

When setting up subdomains, you should make sure that they are immediately keyword optimized and that the content can really only be reached via one path (the main domain). If the content can be reached under other paths, we recommend a 301 redirect set up so that there is no duplicate content.


It makes sense to have your own properties in the Google Search Console because this enables an evaluation per subdomain.

What are directories for?

The directories are an important part of the URL structure and therefore very important for search engine optimization. The search engine crawlers read websites much like directories and data on a hard drive. For example, if all the data were to be located directly under the master data, you would quickly find it difficult to find your way around. The URL structure of your website should therefore also be tidy. The content structure of your page should always include the URL structure and the navigation structure correspond.

The bot can also be managed with a neat structure via the file robots.txt better control. For example, you can exclude the folder / print data / all print versions of the website from the bot.

Subdomain or directory - which makes more sense?

Matt Cutts spoke out in October 2012, saying it was between Subdomains and directories generally hardly make any difference more there. In the past, you could only have a maximum of two results in the SERPs per host (e.g. blog.deineurl.de). Many take advantage of this and outsource all of their content to subdomains so that they could have as many results as possible in the search results.

But now, according to Matt Cuts took the domain (yoururl.de) as the basis for the results and Google can map the content of a subdomain much better to the actual domain. This is to ensure that the search results offered are more diverse.

According to John Müller, directories should be chosen when the contents of a page are as close as possible to one another. At differences in content however, subdomains should be used. Here is his opinion from 2018 at the Google Office Hours:

I did a video about this briefly a while back. I would recommend taking a look at that.

In general, we see these the same. I personally try to keep things together as much as possible, so if it's the same site, then try to put them on the same site essentially. And use subdomains where things are really kind of slightly different.

But there are lots of really strong opinions on this, but from my point of view, this is something that could go either way.

And if you have really strong reasons to go one way or the other, then like obviously, that might be what you’d want to watch out for. On the other hand, if you're like well, I don't care either way, then I would just keep in within the same site.

We want to use specific examples to show how the Directory versus a subdomain structure actually affects.

The advantage of subdomains is that it is often easier to create them. With Domainfactory, for example, you only have to select the domain in the customer menu and then the "Add subdomain" button is displayed. When you have added this, you can install the CRM of your choice on it.

Creating a new directory can be a lot more difficult, especially if you want nice "speaking" URLs.

In the case of a directory, the advantages are otherwise very clear: inheritance of the trust of the domain, link juice, etc.


If you change your existing URL structure, be sure to transfer the old web pages that have already been indexed by Google to your new web pages with the appropriate addresses permanent (301) forward.

The respective advantages for subdomains or directories are summarized in a table:

criteriaOwn domains









Link juice
must be set up individually for each domain

must be set up individually for each domain

Directories benefit
from main page
Trust & Power
must be set up individually for each domain

must be set up individually for each domain

Directories benefit
from main page
must be set up individually for each domain

must be set up individually for each domain

Directories benefit
from main page
Url structure
own URL structure possible

own URL structure possible

URL structure can only be changed to a limited extent
Keyword cannibalization
avoidable with hreflang

avoidable with hreflang

avoidable with hreflang
must be set up individually for each domain

must be set up individually for each domain

only one domain
Risk management
Risk diversification

limited risk diversification

no risk diversification
HTTPS certificates
each domain individually

each subdomain individually

only one domain
Google Search Console & Analytics
each domain individually

each domain individually

only one domain, but own properties for directories possible

According to Matt Cutts, it should be possible that all user signals, links, etc., from which the subdomain benefits, also apply to the main domain, since Google recognizes both as belonging together. The key word here is “should”.

How do the visibility of different domains actually change if you move subdomains to directories and move directories to subdomains?

Examples of change in visibility


An example that has been analyzed on Sistrix is ​​the Case from monster.de (The same applies to other countries as well). Monster.de moved the subdomain structure to directories in 2016.

(c) sistrix.de

Certainly more was done in parallel, but you can see a significant increase in visibility.

The subdomain jobs.monster.de, for example, was found on monster.de/jobs/ moved. You can see here that the directory, despite its "novelty", has a higher visibility after a short time than the subdomain ever had.

(c) sistrix.de


Another example is the side of FC Bayern.

(c) sistrix.de

Not only were many of the subdomains moved to directories, but the domain itself was also converted from .de to .com.

A very strong subdomain was the FC Bayern fan shop (shop.fcbayern.de).

(c) sistrix.de

Here the visibility did not develop as quickly as in the other examples. This could be due to the following reasons:

  • The redirects were not set correctly
  • The fan shop was not in the sitemap at the time of the check
  • Google is just slow

The old url still has rankings and is evolving too.


But what about smaller pages with less visibility?

Among the Sistrix Top 100 winners of 2015 is pkw.de with it. The site is currently with a visibility index around 11.

The visibility of pkw.de has steadily decreased since 2012. Then the subdomains have become directories and voilà, visibility is at a new high.

(c) sistrix.de

Here too, the Subdomain autohaus.pkw.de recognize that the page has considerably more visibility after moving to pkw.de/autohaus/.

(c) sistrix.de


Even if Google can supposedly classify that a certain subdomain belongs to a domain, it doesn't seem to work as well as one might wish. Our recommendation is therefore to use directories as long as there are no major differences in content.