A free, independent guide to creating, configuring and securing subdomains — from DNS records to wildcard SSL certificates — written for site owners, developers and students. Instructions are provider-neutral and work with any registrar or DNS host.
Create Your First SubdomainStep-by-step guide that works for any registrar or DNS provider.
Example DNS Records (Cloudflare format):
What developers and businesses actually use subdomains for.
Separate blog from main site, often on WordPress or Ghost while main site runs on a different stack.
E-commerce store on Shopify, WooCommerce, or custom platform while keeping the brand domain.
RESTful API endpoint for mobile apps and third-party integrations. Standard practice.
Staging/development environment that mirrors production for testing before deployment.
Country/language-specific versions of a site. Common for international businesses.
Web application, SaaS dashboard, or customer portal separate from the marketing site.
Mail server (Postfix, Exchange) or webmail client (Roundcube) access point.
Documentation site, often on GitBook, Notion, or a static site generator like Docusaurus.
System status page (Atlassian Statuspage, Upptime) to communicate service health to users.
The SEO debate, settled with clear use-case guidance.
| Factor | Subdomain (blog.site.com) | Subfolder (site.com/blog/) |
|---|---|---|
| SEO Impact | Treated as separate site | Shares domain authority |
| Technical Separation | Full stack independence | Shared server/config |
| Best for Blog/Content | Only if different CMS needed | Recommended |
| Best for App/API | Recommended | Non-standard |
| SSL Certificate | Separate cert or wildcard | Same cert as main domain |
| Deployment | Fully independent deploys | Tied to main app deploy |
SubDoms is a free, independent reference. These guides and tools cover the rest of a typical subdomain setup.
A, AAAA, CNAME, MX, TXT, NS and CAA records explained, with when to use each.
www, api, blog, cdn, mail, staging and more: what each is usually for and how it is set up.
How search engines treat each option and which to choose for content, apps and regional sites.
Check records, CNAME targets and security headers from your browser using public DNS-over-HTTPS.
Wildcard subdomains, staging environments, SSL options, microservices and takeover prevention.
Quick answers on propagation time, A vs. CNAME, wildcard certificates and SEO.