What Is a Subdomain? Uses & Examples
A subdomain is an extra label to the left of your domain, such as blog.example.in, that can point to its own server, folder or app. It needs its own DNS record and an SSL certificate that covers it, and cookies stay separate by default. For content about the same business, a subfolder is usually better for SEO.
For site owners adding a blog, store, help desk or staging site who need to decide between a subdomain and a folder, and set it up correctly.
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- 5 min
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- 9
- Updated
- 14 Nov 2026
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- WebJi® team
Last editorial update: 14 November 2026. Prices follow the dated sources on this page; checkout confirms current charges.
What is a subdomain, and how does it appear in a URL?
A subdomain is an extra label added to the left of your registered domain — "blog" in blog.example.in — that can point to its own server, folder or application while keeping the parent brand in the address. It behaves as a separate hostname for DNS, SSL certificates, cookies and, often, search engines.
A hostname reads right to left: the top-level domain (.in), then your registered name (example), then any labels in front. "www" is a subdomain too, which is why www.example.in and example.in are two addresses until a redirect joins them.
- Characters: letters, digits and hyphens; each label up to 63 characters, the full name up to 253.
- Nesting: dev.blog.example.in is valid, but every extra level costs typing and trust.
- Cost: subdomains are free to create inside a domain you already own.
How do DNS records point a subdomain somewhere?
A subdomain resolves through its own record in the parent domain's DNS zone: an A record for an IPv4 address, AAAA for IPv6, or a CNAME that aliases it to another hostname. Whoever controls the parent zone controls every subdomain.
blog.example.in. 3600 IN A 203.0.113.25
shop.example.in. 3600 IN CNAME stores.example-platform.com.
mail.example.in. 3600 IN A 203.0.113.40A CNAME cannot share its name with any other record, so a subdomain that needs MX records for email cannot also be a CNAME. TTL sets how long resolvers cache the answer. A subdomain can also be delegated to another DNS provider with its own NS records. Record types are covered in DNS records explained.
Do cookies set on a subdomain reach the main domain?
Not by default: a cookie set by blog.example.in without a Domain attribute is host-only and is never sent to example.in or a sibling subdomain. Setting Domain=example.in makes it readable by every host under that domain, which is what lets a login carry across.
Secure keeps the cookie on HTTPS only and SameSite controls whether it travels with cross-site requests. A portal that must share a session with the main site needs the parent-domain cookie; an app that should stay isolated is safer host-only, because any subdomain can read parent-scoped cookies.
Is a subdomain or a subdirectory better for SEO?
For content about the same business, a subdirectory (example.in/blog) is usually the safer choice because every link and signal stays on one hostname; a subdomain suits a section that is genuinely a separate app, platform or team. Google has said it can handle both, but a subdomain often has to build its own signals.
| Attribute | Subdomain | Subdirectory |
|---|---|---|
| Example | blog.example.in | example.in/blog |
| Search Console | Needs its own property unless you use a domain property | Covered by the main property |
| Cookies | Host-only unless scoped to the parent | Sent with every request to the domain |
| Hosting | Can run on a different server or platform | Same server as the main site, or a reverse proxy |
| Best for | A separate app, store platform, help desk or staging | Blog, guides and service pages for the same brand |
The full trade-off is in subdomain vs subdirectory.
What are subdomains commonly used for?
Common uses are a shop on another platform, a help centre, a customer portal, a staging copy, an API endpoint and mail or webmail hostnames — each needing its own document root, server or release schedule.
Staging needs care: a publicly reachable, indexable staging.example.in competes with the live site for the same content. Put it behind HTTP authentication and a noindex header before the first deploy; the routine is in WordPress staging site.
How do you create a subdomain in a hosting control panel?
In most panels you add the full name (blog.example.in), confirm its document root, and the panel creates both the DNS record and the web server entry; on cPanel this is under Domains › Create A New Domain.
- Confirm the parent domain is on the account and its nameservers point to the host.
- Add the subdomain and keep the suggested document root unless you need another path; untick "Share document root" in cPanel.
- Open the address in a browser; expect a default page or a 403 until content exists.
- Issue an SSL certificate for the new name, then upload files or install the app.
If the parent's DNS is elsewhere (for example Cloudflare), add the A or CNAME record there as well. Panel-specific steps are in create a subdomain in cPanel.
Does an SSL certificate cover subdomains?
A certificate for example.in does not cover blog.example.in unless that name is listed on the certificate or the certificate is a wildcard for *.example.in. Browsers show a name-mismatch error that visitors should not click through.
- Free per-name: Let's Encrypt, included with WebJi® hosting, can issue a certificate for each subdomain.
- Free wildcard: Let's Encrypt wildcards need DNS-01 validation, which requires API access to your DNS.
- Paid wildcard: Sectigo Positive SSL Wildcard is ₹7,500 a year before 18% GST in WebJi® billing; see wildcard SSL certificate.
A wildcard covers one level only: *.example.in covers shop.example.in but not dev.shop.example.in.
What should you check before launching a subdomain?
Treat a public subdomain as its own site: give it unique titles and content, its own sitemap and robots.txt, HTTPS, and links from the main site so crawlers find it.
- Canonicals on the subdomain point to the subdomain's own URLs.
- robots.txt and noindex are checked per host; they do not inherit from the parent.
- HTTPS is enforced with a redirect from http.
- Analytics and Search Console cover the hostname, or its traffic will look like a drop.
Frequently asked questions
Do subdomains cost extra?
No. A subdomain is created inside the DNS zone of a domain you already own, so there is no registration fee. Your hosting plan may limit how many it supports, and a paid certificate for many subdomains is an extra cost.
What is a wildcard subdomain?
A DNS record for *.example.in that answers for any name without its own record. Multi-tenant apps use it to give each customer a hostname, but the web server and certificate must also be configured for those names.
How long does a new subdomain take to work?
Usually minutes, because a brand-new name has no cached answer anywhere. If it still fails after an hour, check that the record exists at the DNS host your nameservers actually use and that the web server has a matching site entry.
Can a subdomain have its own email?
Yes. Add MX records for the subdomain, plus SPF and DKIM TXT records, so addresses such as sales@shop.example.in can receive and send mail. Remember that a name with a CNAME cannot also hold MX records.
Last editorial update: 15 November 2026. Prices follow the dated sources on this page; checkout confirms current charges.
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