What is DNS?
DNS (Domain Name System) is a hierarchical and distributed naming system that translates human-readable domain names (like example.com) into IP addresses (like 192.0.2.1) that computers use to identify each other on the network.
Quick Facts
| Full Name | Domain Name System |
|---|---|
| Created | 1983 by Paul Mockapetris |
| Specification | Official Specification |
How It Works
DNS was designed by Paul Mockapetris in 1983 and is often called the 'phonebook of the internet'. It operates through a distributed database system with multiple levels of servers: root servers, TLD (Top-Level Domain) servers, and authoritative name servers. When you type a URL in your browser, DNS resolvers query these servers to find the corresponding IP address. DNS supports various record types including A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (text), and NS (name server) records. DNS over HTTPS (DoH) and DNS over TLS (DoT) encrypt DNS queries to prevent eavesdropping and manipulation. Major browsers and operating systems now support DoH, with providers like Cloudflare (1.1.1.1) and Google (8.8.8.8) offering encrypted DNS services. This improves privacy but can complicate enterprise network monitoring and filtering.
Key Characteristics
- Hierarchical distributed database system
- Translates domain names to IP addresses
- Uses caching to improve performance
- Supports multiple record types (A, AAAA, CNAME, MX, TXT)
- Operates on UDP port 53 (TCP for large responses)
- TTL (Time To Live) controls cache duration
Common Use Cases
- Website domain name resolution
- Email routing (MX records)
- Load balancing and failover
- Domain verification (TXT records)
- CDN and geographic routing
Example
Loading code...Frequently Asked Questions
What happens when DNS lookup fails?
When DNS lookup fails, your browser cannot resolve the domain name to an IP address, resulting in errors like 'DNS_PROBE_FINISHED_NXDOMAIN' or 'Server not found'. This can be caused by incorrect DNS settings, network issues, or the domain not existing.
What is the difference between DNS over HTTPS (DoH) and DNS over TLS (DoT)?
Both encrypt DNS queries to prevent eavesdropping. DoH uses HTTPS on port 443, blending with regular web traffic and harder to block. DoT uses a dedicated port 853, making it easier for network administrators to identify and manage DNS traffic.
How long does DNS propagation take?
DNS propagation typically takes 24-48 hours but can be faster or slower depending on TTL values. Some changes propagate within minutes, while others may take up to 72 hours to reach all DNS servers worldwide.
What is DNS caching and why is it important?
DNS caching stores previous DNS lookup results locally to speed up future requests. It reduces latency, decreases load on DNS servers, and improves browsing performance. Caches exist at multiple levels: browser, operating system, and DNS resolver.
Can I use custom DNS servers instead of my ISP's?
Yes, you can configure custom DNS servers like Google (8.8.8.8), Cloudflare (1.1.1.1), or OpenDNS (208.67.222.222). Custom DNS can offer faster resolution, better privacy, or additional features like malware blocking.