A sub-domain is a sub-part of a domain name.
A sub-domain exists hierarchically under a domain (lower level) and is dependent on it. A sub-domain often refers to a third-level domain (or even lower).
Sub-domains are used to divide a domain name into independent sub-divisions.
The character . (dot) is used to separate the different levels.
Top-level domains (.com, .fr, .net, .info, .org, etc) are also known as domain extensions, or TLDs (Top-Level Domain).
Format: sub-domain . domain . extension
Example of domain: safebrands.com
Example of sub-domain: subdomain.safebrands.com
In this example "safebrands.com", "safebrands" is a second-level domain positioned under ".com" (a top-level domain).
And for "subdomain.safebrands.com", "subdomain" is a third-level domain, "safebrands" is a second-level domain positioned under ".com" (a top-level domain).
Another example of a sub-domain is "safebrands.co.uk", where "safebrands" is a sub-domain (or third-level domain) positioned under ".co" (a second-level domain) and ".uk" (a top-level domain).
The sub-domain technique allows you to associate a more complete and more meaningful URL or web address with the different contents of your website.
For example, you have created the domain and website example.com / www.example.com.
Your domain name is example.com, with the sub-domain www.exemple.com (www is a sub-domain, or third-level domain).
Using the same model, you can create the subdomain "subdomain" on this website, and you will create it for your domain and also for the subdomain www: this subdomain will then be accessible via the URLs subdomain.example.com and www.subdomain.example.com.
You can associate up to 100 sub-domains with each domain name. You can also define several levels of sub-domains. For example, you could create the sub-subdomain info.blog.example.com to give visitors access to specific content on your site: a blog in this case, with an info section. Each sub-domain name is limited to 25 characters.
The sub-domain "www"
www is a sub-domain like any other.
Are you experiencing sub-domain or redirect problems with www?
Here are the steps to follow if your domain works only with www or does not work with www:
→ My domain works only with www (it doesn't work without www) ...
If www.example.com works but example.com doesn't work.
Add a web redirect to reroute example.com to www.example.com:
- Choose type 301 (permanent non-transparent redirect)
- Leave the "subdomain" field empty
- Enter www.example.com in the "Redirect URL" field by replacing example.com with your domain name.
- Then click on "Submit".
→ My domain does not work with www ...
If example.com works but www.example.com doesn't work.
Add a web redirect to reroute www.example.com to example.com:
- Choose type 301 (permanent non-transparent redirect)
- Enter “www” in the "sub-domain" field
- Enter example.com in the "Redirect URL" field by replacing example.com with your domain name.
- Then click on "Submit".
That's all!