Add-on domain vs Subdomain vs Subdirectory

This is an article about “Add-on domain vs Subdomain vs Subdirectory”. It’s a reply to a member’s question.

Here’s her question:

“Hi Kenneth, just like to know exactly what is the difference between an add-on and a sub domain, and what do you use each one for? I know you can host several different websites, or pages but, which do you use for what?” – Glenda

Hi Glenda, an add-on domain is a new domain, such as,, You have to buy a new domain name whenever you want to add an add-on domain to your hosting account. A sub-domain is a domain derived from your existing domain. Let’s say your existing domain is, you can have unlimited sub-domain such as, and so on.

Whenever you want to start a new project, there are 3 types of website structure you can consider.

1) A brand new domain (i.e. an add-on domain)
2) A subdomain
3) A subdirectory (simply a sub-folder of your domain)

If you are starting a new project in a completely different niche, it’s obvious that you should buy a new domain and host it as an add-on domain. But if you are starting a new project in the same niche, you will have to think which of the 3 structures above you should adopt.
Let’s say you have a website called, and you are thinking of starting a blog related to online success, you have 3 options to structure your new blog.

1) A brand new domain – you can call it
2) A subdomain – you can call it
3) A subdirectory – you can call it

Below are some issues you should consider when deciding which option to choose.

1) From SEO perspective

If your original website is already well established, with a decent PR, you may NOT want to start a brand new domain just for your blog. This means option 1 is out.

If you use option 2 or 3, you can pass the credibility of your original domain to your blog, which is in either a subdomain or subdirectory. This will help your new blog and subsequent blog posts to get ranked in the search engines faster and better. Also your new blog content will help boost your original website. So it’s a win-win situation.

2) From branding perspective

If you plan to brand your blog in the future, then you should start a new domain called In general, as long as you intend to brand your new project as a new entity, it’s always a good idea to register a new domain for it.

3) “Expandability” issues

If you envision that your blog is going to be very big and it may require a lot of server resources, then it may be a good idea to start your blog in a new domain or subdomain, not a subdirectory.

To understand why, let me explain the technical difference between a subdomain and subdirectory. A subdomain can be technically treated as a new domain, in the sense that it can be hosted separately from its root domain. This means you can have and hosted on different servers. But this cannot be done for

As such, if you expect your blog (or whatever new project you have) to consume a lot of server resources, your current server may not be sufficient to satisfy your needs. In such case, if you start your new project in a new domain or subdomain, you can always host it on another server in the future.

One good example is is a brand. Everything it does must enhance its brand “Google”. So when Google started Google Map, which obviously requires a lot of server resources, it only has 2 choices. Google can either call it or

And you should know their decision. It’s logical to make that decision too. They call it

4) To boost your Alexa ranking

More and more people, especially in the internet marketing niche, look at the Alexa ranking of a website as a means to gauge the credibility of the website. So if you want to boost the Alexa ranking of your website, it may be a good idea to put all your projects under one domain. This means you can either use a subdomain or subdirectory.

Take Google and Yahoo as a case study. Google names its international websites in separate domains, such as, but Yahoo names its international websites as a subdomain, such as The result is is now ranked #1 in Alexa ranking. I believe if Google were to consolidate all its international websites under, it should rank #1 in Alexa ranking.

The Conclusion?

There is no conclusion. It really depends on what you want to do now and in the future. New domain costs money but it looks professional. Subdomain is free and it’s technically as flexible as a new domain, but it’s not as professional. Yet, if you want to create a mega website like, subdomain can give you a lot of leverage. Subdirectory is the simplest option for website structuring. If branding and server requirement are non-issue, it’s always easier to just use a subdirectory.

30 thoughts to “Add-on domain vs Subdomain vs Subdirectory”

  1. I think Kenneth pretty much sums it up very well.

    The differences between a subdomain and a subdirectory is very fine, because subdomain hosted on the same server exists as a subdirectory inside that server. I guess the difference really comes down to migration when you outgrown your subdomain/subdirectory.

    Reading Kenneth’s post seems to suggest it is easier to migrate a, than to migrate Not sure if this conclusion is right, Kenneth?

    Willy Lim
    Net Profit Quest Business Coach
    The Financially Free Advisor
    Making InterNET work for Marketing in Asia

  2. Thank you Kenneth!!! I did ask this question to someone who I am on their list, and they obviously did not know, as they gave a silly answer, and then went on to try to sell me something.( their answer was NOTHING even remotely like yours) So thank you, when you are poking around cpanel there is a lot to understan.
    Regards Glenda.
    P.S I unsubscribed to that list..wouldn’t have done so if the bloke had of been honest about it.

    1. I think you’re referring to using subdomain for different websites. Personally, I don’t think it’s a good idea. First, Google treats subdomain as a new domain. Second, link building for subdomain is generally harder as you can’t do things like directory submission.

  3. On one of my site I created subdomains for each of the different section but each subdomain had 1 page only.
    Do you think I shall change it to sub directory instead or add more content to subdomains?

  4. I have been doing some research on this topic and according to the folks at Alexa, they do not track traffic to your subdomain. They only track traffic to your main home page.

    I am having a problem currently with getting accurate stats from Alexa because they are only tracking traffic to my main homepage and not my Unfortunately, the main homepage gets next to nothing traffic while the blog gets about 10,000 unique visitors per month.

    So consider that when choosing a subdomain. If showing a legitimate traffic ranking is important then it can be a nightmare to get Alexa to figure out what is what.

  5. Thank you for making it clear, Kenneth!

    Kenneth, do you have any idea how it would affect the SEO of my website if I created a subdomain or a subdirectory for my website, but also purchased a new domain and forwarded it to the subdomain or subdirectory? Since the new domain would ultimately take them to my website, I wouldn’t think it would hurt my SEO – would you?

    Thank you!!!
    Julie :)

  6. Thanks for explaining this so clearly Kenneth, I’ve been wondering how this works for some time. I’m starting a site that will have a wiki on it so I know now to put it in a subdomain and save myself a lot of headache down the line!

    Best wishes.

  7. i searching the answer about the ranking relationship between add-ons domain, subdomain, and subdirectory.

    Very Good Articles.. Will help for newbie like me.. :)

    Many thanks Kenneth

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