The DNS Zone File held by the Authoritative Nameserver for a domain is actually quite extensive, and you can manipulate it somewhat using subdomains Consider the side of the Internet visible to web users and show you how subdomains work(and can improve your website.
Get creative with subdomains for your DNS
An FQDN requires a hostname as well as a domain name. This means that any domain name can actually be split into multiple subdomains.
Picture it like an apartment building — not just any old apartment building either, but a fairly swanky apartment building.
The first floor of the apartment building has an open space that has plenty of comfortable seating and refreshments available. It’s a common area that can be used by all residents of and visitors to the apartments.
If somebody told you she lived at 123 Example Street, Exampleton, then you would assume that when you arrived you simply needed to go through the front door to find her. However, in this swanky apartment building that would only get you to the communal area on the first floor. To find the actual apartment, you would need to know the specific apartment number.
So the complete address would be Apartment 45, 123 Example Street, Exampleton. After you have this correct, full address you can navigate straight to the apartment.
This is also true of websites. If you give somebody your website address with no hostname at the beginning, it is like providing your apartment address without your apartment number. That’s okay if you live in a house rather than an apartment (or, in website terms, you only require a site to have the default hostname).
However, the flexibility of the DNS means that at any time you can create a subdomain by creating a new hostname, you can have a second, third, and fourth (and so on) website all underneath one domain name.
For example, you may convert the upstairs of your house into an apartment for your mother-in-law to live in. Your mother-in-law can then get her own mail and give out her own address as Apartment A, 456 Sample Street, Exampleton.
Likewise, say you’re running a website for your local football team, examplefootballteam.com, and the coach decides he wants to have his own blog. You can create a subdomain with its own hostname of coach, which will give him his own unique address to make his own site, still under the umbrella of examplefootballteam.com.
In this example, the FQDN of the coach’s blog would be coach.examplefootballteam.com.
Both coach.examplefootballteam.com and www.examplefootballteam.com are FQDNs, meaning they are both unique and can therefore point to different places online.
In theory, you can have as many subdomains as you need under your domain, but some of the cheaper web hosts may limit the maximum number they allow you to create.
You can get as creative as you like with your subdomains and are limited only by your imagination and your requirements. Some people never require a subdomain, whereas others create a seemingly endless stream of them.
Just to get your creative juices flowing, the following list includes a few ideas of how you might want to use subdomains:
You may have purchased the domain yourfamilyname.com and created a personal website there. You may then want to give your children the opportunity to have their own websites and so you create a subdomain for each of them — for example, Sandra.yourfamilyname.com, Philip.yourfamilyname.com, and Alex.yourfamilyname.com.
Your company’s website may be yourawesomebusiness.com, and you may want to create another site where you give support for your products, which you could call support.yourawesomebusiness.com. You may wish to create another site where you have a forum for your customers to talk about how awesome your products are, called forum.yourawesomebusiness.com.
Say your name is Gemma and you spend all your spare time doing arts and crafts and have built a website called gemmasartsandcrafts.com to show people some of your beautiful items.
Only after you started building the site did you realize that the papier-mâché models you create are really of little interest to the people interested in needlework or oil painting. You can create separate sites for each type of craft, each with its own subdomain, such as oilpainting.gemmasartsandcrafts.com and needlework.gemmasartsandcrafts.com as well as having your main site at gemmasartsandcrafts.com.
How to create a new DNS subdomain
Most control panels provide you with a simple way to create new subdomains.
The process for setting up a subdomain is essentially the same for most control panels. As an example, here’s how you do it in cPanel:
Log in to cPanel with the details your host provided when you opened the account.
Scroll to the Domains section and click Subdomains.
Type the name of the new subdomain you want to create in the box.
Select the domain for which you want to create a subdomain.
Any add-on or parked domains you have set up will be available in the drop-down box.
If you want to, type the path to the document root of the domain.
By default, the system selects /public_html/TheSubdomainYouTyped, but you can change it if you need to.
Do not change the document root unless you are certain you know what you are doing. Changing the document root can make the setup very confusing.
Click Create.
The subdomain shows up in the list at the bottom of the page. You can remove it by clicking Remove or, if you need to, you can redirect it.
If you need to redirect a subdomain for a domain, it must first be set up as a subdomain, either through the automatic process or manually. Otherwise the DNS does not know of its existence and the redirect does not work.