What is a subdomain?
Author: Domeny.ForSale editorial team Published
In brief: A subdomain is an address created within another domain, such as sklep.przyklad.pl within przyklad.pl. It lets you separate a shop, application or another part of a website, including hosting it separately. You usually do not need to register it separately, but you do need to configure it in DNS and in the service it should point to.
How do you recognise a subdomain in an address?
In the address blog.przyklad.pl, the word blog identifies a subdomain created under przyklad.pl. Domain names form a hierarchy: additional components added on the left let you create more specific addresses. You can therefore also create pomoc.sklep.przyklad.pl, although long names can be inconvenient for users.
The familiar www is also a subdomain. The addresses www.przyklad.pl and przyklad.pl do not necessarily display the same website automatically — their behaviour depends on the configuration. If they should lead to one website, one address is usually chosen as the primary address, with the other redirecting to it.
A subdomain does not have to represent a website. It can serve as the address of a mail server or another service. However, the name alone, such as poczta.przyklad.pl, does not activate email: a properly configured service is also needed.
Subdomains, directories and separate domains
A subdomain appears before the domain name, while a directory in a web address appears after a slash. The address przyklad.pl/blog/ identifies a path within the same website; it does not necessarily correspond to a physical folder on the server.
| Option | Example | Typical use |
|---|---|---|
| Subdomain | blog.przyklad.pl | A blog running as a separate website |
| Directory | przyklad.pl/blog/ | A section of the main website |
| Separate domain | innyprojekt.pl | An independent brand or project |
A subdomain does not require separate registration with a domain registrar if you control its parent domain. A separate domain, by contrast, must be registered and renewed independently. All subdomains depend on the parent domain being maintained: losing control of przyklad.pl can also put services under its subdomains at risk.
Creating a DNS record usually does not involve a separate fee for the name, but that does not mean the entire website will run for free. Hosting, an external platform or a service plan may have fees and limits on the number of addresses supported. Check these conditions in the provider’s current documentation and pricing.
When should you choose a subdomain rather than a directory?
A subdomain is useful when part of a project requires a different technical setup. A company might maintain its informational website at przyklad.pl and a customer application at panel.przyklad.pl. Both addresses remain associated with the same brand, but they can run on different servers and be deployed independently.
Suppose you run a service business website and want to add guides using the same content management system. The directory przyklad.pl/poradniki/ will usually be the simpler choice: you can retain shared navigation, a common template and the same publishing workflow. If, on the other hand, you are launching an external training platform, the subdomain akademia.przyklad.pl may make it easier to connect without moving the main website.
There is no rule that a subdomain always helps or harms visibility in Google. Factors include page accessibility, content, linking and correct configuration. A separate website may require separate oversight of indexing, analytics and navigation; changing the address alone does not guarantee better rankings.
How do you create a working subdomain?
You need access to DNS management and to the hosting service or destination platform. DNS is the system that indicates where to direct traffic for a given name. The DNS control panel may be with a different provider from the company where the domain was registered.
- Add the address to the destination service. In the hosting or application control panel, enter an address such as
sklep.przyklad.pl. The provider should supply the required DNS settings. - Create the appropriate DNS record. An A record points to an IPv4 address, an AAAA record to an IPv6 address, and a CNAME points a name to another domain name. Choose the option specified by the provider rather than copying an arbitrary configuration.
- Enable HTTPS. The TLS certificate, which enables an encrypted connection, must cover the specific subdomain. A certificate issued only for
przyklad.pldoes not automatically coversklep.przyklad.pl. - Check that it works. Once DNS caches have reflected the changes, test the address, certificate, redirects and the website’s most important functions.
Some control panels perform several of these steps automatically. However, a DNS record alone is not enough to display a page: the server must also recognise the subdomain and serve the correct website.
What should you remember when maintaining a subdomain?
A subdomain is not an access-control measure. The address test.przyklad.pl may be publicly accessible even if you never link to it anywhere. A test version or internal dashboard should be protected with authentication or access restrictions; preventing indexing is no substitute for these safeguards.
After you stop using an external platform, remove unnecessary DNS records. In certain configurations, a record left pointing to an inactive service may allow someone to take over the subdomain.
Before creating a new address, establish where the service will run and who is responsible for maintaining it. If you do not need a separate environment, first check whether an ordinary section of the existing website would accomplish the task more simply.
See also: What happens after a domain expires?
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