Subdomain

What's the difference between a subdomain and a subfolder?

A subdomain adds a name in front of your address (shop.yourbusiness.kr), while a subfolder adds a path after it (yourbusiness.kr/shop). They look similar, but they're created in different places and used for different things.

A subdomain is created in DNS and can point to a completely different server or service. A subfolder is a page within the same website, so it's managed on the same server and in the same admin panel.

The rule of thumb is simple. Remember "if you need to attach another company's service, use a subdomain; if it all stays inside your website, use a folder," and you'll be right most of the time.

For example, if a Korean restaurant puts its menu at yourbusiness.kr/menu and an outside booking service at book.yourbusiness.kr, it can manage the menu along with the website while using the booking service's features as they are.

When should you use a subdomain?

Subdomains are most often used to attach a service other than your website so it looks like part of your business's address. If you connect separately run pages, like a booking, shopping or survey service, at something like book.yourbusiness.kr, customers feel they're moving around inside the same business.

They're also used by businesses with several locations to separate each branch's information, or to put up a preview site before launch. For example, a cafe running a coffee-bean subscription shop separately from its main website might attach store.yourbusiness.kr.

On the other hand, for content that stays within one website, like your about page, menu or blog, a subfolder is simpler than a subdomain. You don't add more things to manage, and it's easier for search engines to show it all as one site.

Keep in mind that an outside service attached on a subdomain may have a different design and menu from your main website. So customers don't suddenly feel they've landed at a different business, match your logo and colors, and always include a link back to your main website.

• www: your main website (the most common subdomain)
• shop or store: a separately run online shop
• book or reserve: an outside booking service
• blog: when attaching a separate blog service
• preview or dev: a preview site before launch

How many subdomains can you create, and how much do they cost?

Once you have a main domain, you can create as many subdomains as you need in DNS without buying anything extra. Creating them usually costs nothing; any charges come separately from the service or server you attach to that address.

But the more you have, the more you have to keep track of. For each subdomain, you need to check that the connected service is still running and that your https certificate covers that address too. You can get a certificate for each address separately or use one certificate that covers all subdomains at once.

For a small business, one main address plus one or two subdomains you really need is usually plenty. If you don't have a clear plan to use one, it's easier to manage if you don't create it in advance.

How do you create a subdomain?

You create a subdomain by adding one record line in your domain's DNS settings. In most cases, you enter the address given by the service you're connecting as a CNAME record.

The values differ from service to service, so copying another service's values won't work. If the service's setup screen has a "Verify connection" button, press it a few hours after adding the record and it will tell you whether the connection works.

1. 01Decide on the name to put in front. (Example: short, clear English words like shop, book or blog)
2. 02In the settings of the service you're connecting, find the "Connect your domain" instructions and the values to enter.
3. 03In your registrar's DNS settings, add a CNAME (or A) record with that name.
4. 04Register the same subdomain address on the service's side too.
5. 05A few hours later, check that the address opens and shows no https warning.
6. 06Link the new address from a menu or button on your main website.

How do www and subdomains show up in search?

Google may treat the address with www, the one without it, and other subdomains as separate addresses. So if the same content opens at several addresses, Google advises choosing one as the main address and automatically forwarding the rest to it.

If you add your site to Google Search Console as a "Domain" property, you can see www and all subdomains together. This type is verified by adding a verification record to your DNS. If you add it as a "URL prefix" property instead, you only see the one address you entered, so you have to add each subdomain separately.

Search engines can handle both subdomains and subfolders, but subdomains often need their own Search Console setup and visitor analytics settings, which means more to manage. For example, if a hair salon plans to post customer reviews and hair-care tips regularly, putting them under the main address, like yourbusiness.kr/blog, is a safer bet than blog.yourbusiness.kr.

What are common mistakes when using subdomains?

The most common mistake is leaving subdomain records in place after you're done with them. If a record still points to a service that has ended, the address may show an error page, or in rare cases someone else can take over that spot on the service and display something unrelated at your address.

Sometimes a pre-launch preview subdomain gets picked up by search engines. Ask your agency to password-protect preview addresses or set them to be excluded from search.

When you create a subdomain, jot down the name, what it's for and when you created it. Even if you change agencies years later, this list makes it easy to tell which records can be deleted and which must stay.

• No leftover subdomain records point to services you don't use
• Preview addresses are blocked from showing up in search
• You're not adding subdomains where a subfolder would do
• Subdomain addresses also open without https warnings