A subdomain is an extra name added to the front of your domain, like shop.yourbusiness.com.au or book.yourbusiness.com.au. It costs nothing to register, and it can point to a different server or service from your main website. Use one when part of your business runs on a separate platform. Keep your blog, services and landing pages in folders on the main site instead.
Key takeaways
- A subdomain is free and is created with a DNS record, not a new registration.
- It suits separate systems: an online shop, a booking tool, a client portal or a staging copy.
- For content you want found in Google, a folder (yourbusiness.com.au/blog/) is usually simpler to manage.
- Delete the DNS record when you stop using a subdomain, or someone else may be able to claim it.
What is a subdomain, exactly?
Your domain name has parts. Reading from the right, there’s the extension (.com.au), then the name you registered (yourbusiness). Anything you add to the left of that is a subdomain. Even “www” is a subdomain.
Each subdomain is just a DNS record that tells browsers where to go. So the work happens wherever your domain and DNS management lives, not at the point of registration.
How is a subdomain different from a subdirectory?
A subdirectory (or folder) sits after the domain: yourbusiness.com.au/shop/. A subdomain sits before it. They look similar but work differently.
| Subdomain | Subdirectory | |
|---|---|---|
| Example | shop.yourbusiness.com.au | yourbusiness.com.au/shop/ |
| Can run on a different server or platform | Yes | Rarely, and it takes extra setup |
| Set up with | A DNS record | A page or folder on your website |
| Best for | Separate systems | Content that belongs to the main site |
Google’s own guide to sites for different regions sums up the trade-off. It lists subdomains as easy to separate and able to sit in different server locations, and subdirectories as low maintenance because they share one host (Google Search Central).
Is a subdomain or subdirectory better for SEO?
Google hasn’t said that one ranks better. The differences are practical: a subdomain usually has its own sitemap, settings and platform. In Search Console, a URL-prefix property doesn’t include subdomains such as m.example.com, so you need a Domain property to see everything in one place (Google Search Console Help).
In our experience, small businesses do better keeping their blog, service pages and location pages in folders on the main site. Splitting a blog onto blog.yourbusiness.com.au adds work and rarely brings any benefit.
When should you use a subdomain?
Use a subdomain when the thing you’re adding runs somewhere other than your website:
- An online shop on a hosted platform, such as shop.yourbusiness.com.au, while your main site stays on WordPress.
- A booking or appointment system that the software provider hosts for you.
- A client portal or billing system, kept apart from the public site.
- A staging copy for testing changes before they go live, hidden from search engines.
- A help centre or knowledge base run on a support tool.
Blog posts, service pages and ad landing pages belong in the main site instead.
How do I create a subdomain?
- Choose a short, obvious name. shop, book, portal or help.
- Set up the destination first. Add the subdomain in the hosting account or service that will run it, before touching DNS.
- Add the DNS record. Usually an A record pointing to a server’s IP address, or a CNAME pointing to the service’s hostname. Add it wherever your DNS is hosted. If you’re not sure where that is, our guide to nameservers vs DNS explains how to tell.
- Turn on SSL. Each subdomain needs a certificate covering it. A wildcard certificate covers every subdomain at once, and Let’s Encrypt issues them only through a DNS check (Let’s Encrypt).
- Test, then write it down. Check it loads securely, then add it to your list of domains and services.
What can go wrong with subdomains?
The biggest risk is a forgotten one. Say you cancel a booking tool but leave its DNS record in place. If the provider doesn’t verify ownership, someone else may claim your subdomain there and publish their own content under your name. This is called a subdomain takeover. MDN’s advice is simple: when you retire a service, remove the DNS record first (MDN).
Subdomains can also share login cookies. A cookie set for your main domain is available to all its subdomains (MDN). Point subdomains only at services you trust.
Every subdomain also depends on the main domain. If it lapses, everything on it stops. Check who owns my domain on the record, and make sure renewals go to someone who’ll act on them.
Do subdomains need their own registration or privacy?
No. There’s no separate registration, renewal or WHOIS record for a subdomain. What the public can see is the record for the main domain, which our guide to domain privacy Australia explains. If you’re moving a subdomain’s site into a folder, or changing hosts at the same time, free website migration on our hosting plans covers the move.
Want your domain, DNS and hosting in one place? You can register your domain with WMS and we’ll keep the records tidy for you.
Frequently asked questions
Does a subdomain cost extra?
Not to create. A subdomain is a DNS record on a domain you already hold. You may still pay for whatever runs on it, such as a booking tool, a shop platform or an extra hosting account.
Is www a subdomain?
Yes. Most sites pick one version, with or without www, and redirect the other to it, so visitors and search engines always land on the same address.
How many subdomains can I create?
As many as you need, within your DNS provider’s limits. The real limit is keeping track. Keep a list of each subdomain, what it points to and who manages it, and remove any you no longer use.
Should my blog be on a subdomain?
Usually not. A blog in a folder, like yourbusiness.com.au/blog/, sits inside your main site, shares its settings and links naturally to your service pages. A subdomain adds separate setup for little benefit.
Sources
- Managing multi-regional and multilingual sites, Google Search Central
- Add a website property to Search Console, Google Search Console Help
- FAQ, Let’s Encrypt
- Subdomain takeovers, MDN Web Docs
- Set-Cookie header, MDN Web Docs