Chapter 9: Domain Names, DNS and Subdomains
9.1 What is a domain name?
In short: A domain name is a human-friendly label for an IP address.
A domain name is a human-friendly label for an IP address. Read it from right to left:
blog . example . com .
| | | └── root (the invisible dot)
| | └────── TLD: top-level domain (.com, .in, .org, .dev)
| └────────────── second-level domain: the name you buy
└────────────────────── subdomain: you create as many as you want, free
| Term | Meaning | Example |
|---|---|---|
| TLD | Top-level domain, managed by a registry | .com, .in, .org, .dev, .co.in |
| Domain / apex / root domain | The name you register | example.com (in DNS consoles often written @) |
| Subdomain | Any name to the left of your domain | www.example.com, blog.example.com |
| FQDN | Fully qualified domain name, the complete name | api.example.com. |
| Registrar | Company that sells/renews domains for you | GoDaddy, Namecheap, Hostinger, Route 53 Domains |
| Registry | Organisation that runs a TLD | Verisign (.com), NIXI (.in) |
| DNS hosting / name servers | Servers that store your records and answer queries | ns51.domaincontrol.com (GoDaddy), ns-123.awsdns-15.com (Route 53) |
| Web hosting | The machine that serves the website | Your EC2 instance |
Ravindra Bagale's Tip
Keep three things separate in your head: who you bought the name from (registrar), who answers DNS questions (name servers), and where the website runs (EC2). They can be three different companies. Students mix them up and then search for "EC2 settings" inside GoDaddy. Once this picture is clear, DNS becomes very simple.