The last segment of a domain name (e.g., .com, .org, .io), representing the highest level in the DNS hierarchy after the root.

TLD (Top-Level Domain) - What It Means & How It Works

What is a TLD?

A TLD (Top-Level Domain) is the rightmost segment of a domain name—the part that comes after the final dot. In "example.com", the TLD is ".com". TLDs sit at the top of the DNS hierarchy, just below the root domain, and are managed by designated registry operators under ICANN oversight.

Types of Top-Level Domains

TLDs are categorized into several types, each with different purposes and registration requirements:

Generic TLDs (gTLDs)

Originally limited to .com, .net, .org, .edu, .gov, .mil, and .int, the gTLD space exploded after ICANN's 2012 New gTLD Program. Today, there are over 1,200 gTLDs including:

Legacy gTLDs: .com, .net, .org
Sponsored gTLDs: .edu, .gov, .museum
New gTLDs: .app, .dev, .io, .xyz, .blog, .shop

Country Code TLDs (ccTLDs)

Two-letter TLDs assigned to countries and territories based on ISO 3166-1 alpha-2 codes:

.us (United States)
.uk (United Kingdom)
.de (Germany)
.jp (Japan)
.io (British Indian Ocean Territory, popular with tech companies)

Infrastructure TLD

The .arpa TLD is used for technical infrastructure purposes, particularly reverse DNS lookups.

How TLDs Work in DNS

When you request a domain, DNS resolution starts at the root and works down:

1. Query root servers → "Who handles .com?" 2. Root returns: "Ask Verisign's .com servers" 3. Query .com servers → "Who handles example.com?" 4. TLD returns: "Ask ns1.example.com"

5. Query authoritative server → Get IP address

Each TLD has designated authoritative name servers that know about all domains registered under that TLD.

TLD Selection for Your Project

Choosing the right TLD impacts your brand, SEO, and user perception:

For Businesses

.com remains the gold standard for commercial websites. Users instinctively add ".com" when typing domains, and it carries universal recognition and trust.

For Technology Companies

.io has become the de facto TLD for tech startups, SaaS products, and developer tools. Other popular tech TLDs include .dev, .app, and .tech.

For Organizations

.org traditionally signals non-profit or community organizations, though registration is open to anyone.

For Specific Industries

New gTLDs offer industry-specific options: .shop for e-commerce, .blog for content sites, .design for creative professionals.

TLD Availability and Pricing

TLD availability varies significantly:

Open TLDs: Anyone can register (.com, .net, .org, .io) Restricted TLDs: Require verification or eligibility (.edu requires accredited institutions, .gov requires government entities) Premium TLDs: Some TLDs charge premium prices, particularly newer gTLDs and certain ccTLDs

Checking TLD Coverage

Domain availability APIs like DomScan support different TLDs based on RDAP/WHOIS availability. Use the coverage endpoint to see which TLDs are supported:

curl "https://domscan.net/v1/coverage"

TLD Considerations for Developers

When building domain tools, consider:

RDAP Support: Not all TLDs have RDAP servers; some only support WHOIS
Rate Limits: Each TLD registry has different rate limiting policies
IDN Support: Some TLDs support internationalized domain names, others don't
Registration Rules: Some TLDs have specific character or length requirements

Understanding TLDs is fundamental to working with domain availability checking and registration systems.

TLD (Top-Level Domain)