What is DNS? Complete Beginner’s Guide to Domain Name System

What is DNS? Complete Beginner’s Guide to Domain Name System

DNS (Domain Name System) is the phonebook of the internet — it translates human-friendly domain names into IP addresses so browsers can load websites.

What is DNS?

DNS (Domain Name System) is a distributed naming system that maps domain names like coresectech.com or google.com to machine-readable IP addresses (for example 142.250.183.14). Instead of remembering numbers, users type easy names—DNS handles the lookup behind the scenes.

Why DNS is Important

  • User convenience: We use memorable domain names instead of numeric IPs.
  • Scalability: DNS is distributed across many servers, allowing the internet to scale globally.
  • Flexibility: DNS records let administrators move services (web, mail) between servers without changing the domain name.

How DNS Works — Step by Step

  1. User request: You type a domain name in the browser (e.g. example.com).
  2. Recursive resolver: Your device asks a DNS resolver (usually your ISP’s resolver or a public resolver like Google DNS).
  3. Root and TLD lookup: If needed, the resolver queries root servers, then the TLD (like .com) name servers.
  4. Authoritative name server: The resolver retrieves the authoritative server that holds the actual record for the requested domain.
  5. Response: The IP address is returned to your device and the browser connects to the web server.

Resolvers and caches reduce lookup time—once a resolver knows an address (for a set time), it can answer repeated requests quickly.

Common DNS Record Types (Quick)

  • A: Maps a domain to an IPv4 address.
  • AAAA: Maps to an IPv6 address.
  • CNAME: Alias of one name to another.
  • MX: Mail exchange record (which server handles email).
  • TXT: Text records (used for SPF, DKIM, verification).

Common DNS Problems & Quick Fixes

Here are frequent DNS issues and simple troubleshooting steps:

  • DNS server not responding: Restart your router or switch to a public DNS (example: 8.8.8.8 or 1.1.1.1).
  • Slow resolution: Use a faster resolver (Cloudflare or Google), or check for ISP issues.
  • Misconfigured records: Verify A, CNAME, MX, and TTL values in your DNS host panel.
  • Propagation delay: DNS changes can take time to propagate—be patient and check with dig or online DNS checkers.

How to Change DNS on Your Device (Simple)

Windows: Network settings → Adapter properties → IPv4 → Use the following DNS server addresses → Enter 8.8.8.8 and 8.8.4.4 (Google) or 1.1.1.1 (Cloudflare).

Android / iOS: Wi-Fi settings → Modify network → Advanced DNS settings or use DNS apps that support custom resolvers.

Practical Tools for DNS Troubleshooting

  • dig — command line DNS lookup (Linux, macOS, WSL)
  • nslookup — built-in Windows DNS query tool
  • Online checkers — DNS Propagation Checker, MXToolbox

Conclusion

DNS is essential for the internet to function smoothly. For anyone working in networking or system administration, understanding DNS concepts—records, resolvers, propagation and troubleshooting—is a foundational skill that saves time and reduces outages.

FAQ

Q: What is DNS in simple words?

A: DNS is like a phonebook for the internet: it converts domain names to IP addresses.

Q: How long do DNS changes take to update?

A: It depends on TTL; typically anywhere from a few minutes to 48 hours for full global propagation.

Q: Which public DNS is best?

A: Google DNS (8.8.8.8) and Cloudflare (1.1.1.1) are both fast and reliable for most users.