Domain Hierarchy
Domain names read from right to left in a hierarchy:
- Root Zone: The empty name at the top (.).
- Top-Level Domain (TLD): Suffixes like .com, .org, or country-code TLDs like .uk.
- Second-Level Domain: The primary name you register (e.g. example).
- Subdomain: Extensions prefixing the primary name (e.g. blog.example).
Registries vs Registrars
A Registry controls the master database for a TLD (e.g. Verisign owns the .com registry).
A Registrar is an accredited company (e.g. Namecheap, GoDaddy) licensed to lease domain registrations to public users, updating records with the parent registry on their behalf.
The Zone Apex
The zone apex (also called the naked domain or root domain, e.g. example.com) represents the parent level of the domain zone. Due to RFC design, CNAME records are blocked at the zone apex, requiring A/AAAA records or provider-specific ALIAS workarounds.