Comprehensive Top-Level Domain (TLD) Reference Guide

A comprehensive reference guide to Top-Level Domains (TLDs), including generic TLDs, country-code TLDs, and specialized domains for developers and system administrators.

This article serves as a comprehensive reference for Top-Level Domains (TLDs) - the highest level in the hierarchical Domain Name System (DNS). Whether you’re a system administrator, web developer, or domain researcher, this guide provides essential information about the various types of TLDs and their purposes.

A Top-Level Domain (TLD) is the last segment of a domain name, located after the final dot. For example, in example.com, the TLD is .com. TLDs are managed by the Internet Assigned Numbers Authority (IANA) and are essential components of the internet’s addressing system.

These are the original TLDs established in the 1980s:

Introduced after 2012 to expand domain options:

Country-specific TLDs managed by individual countries:

Specialized TLDs with specific purposes and restrictions:

Popular TLDs for URL shortening services:

• .ly (bit.ly)
• .co (t.co)
• .gl (goo.gl)
• .tt (ift.tt)

Commonly used for development:

• .dev (Google-owned, HTTPS required)
• .test (reserved for testing)
• .localhost (local development)

• .bank and .insurance require enhanced security
• .gov restricted to government entities
• .edu restricted to educational institutions

1. Primary choice: .com for maximum recognition
2. Alternative: Country-specific ccTLD for local presence
3. New options: Industry-specific TLDs (.tech, .shop, .services)

1. .dev - Google-owned, HTTPS enforced
2. .io - Popular in tech community
3. .tech - Technology-focused
4. .app - Application development

1. .org - Traditional non-profit choice
2. .foundation - Foundations and charities
3. Country-specific for local organizations

example.com.    IN    A    192.0.2.1

www.example.com.    IN    CNAME    example.com.

example.com.    IN    MX    10    mail.example.com.

# Get root name servers
dig . NS

# Query specific TLD name servers
dig com NS
dig org NS

# Get SOA record for TLD
dig com SOA

# General domain info
whois example.com

# TLD registry info
whois -h whois.iana.org com

# Using nslookup
nslookup example.newgtld

# Using host command
host example.newgtld

1. DNS Propagation: New TLD records may take 24-48 hours to propagate globally
2. DNSSEC: Many new TLDs support DNSSEC validation
3. HTTPS Requirements: Some TLDs (.dev, .app) require HTTPS
4. Rate Limits: Registry operations may have rate limits
5. Registry Policies: Each TLD has specific registration policies

• IANA Root Zone Database: https://www.iana.org/domains/root/db
• ICANN New gTLD Program: https://newgtlds.icann.org/
• Public Suffix List: https://publicsuffix.org/

This reference guide covers the major categories of TLDs available today. The domain landscape continues to evolve with new TLDs being introduced regularly. When selecting a domain, consider your audience, purpose, and technical requirements. For system administrators and developers, understanding TLD structure is crucial for DNS management, security configurations, and global accessibility.

Keep this reference handy for domain planning, DNS configuration, and troubleshooting domain-related issues in your infrastructure.