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DNS

The Domain Name System (DNS) is a fundamental component of the internet that translates human-readable domain names (like example.com) into IP addresses that computers use to identify each other on the network. DNS acts as the "phonebook" of the internet, enabling users to access websites and services using easy-to-remember names instead of numerical IP addresses.

🧩 How DNS Works​

  1. User Request: You enter a domain name in your browser.
  2. DNS Resolver: The request goes to a DNS resolver, which queries DNS servers to find the corresponding IP address.
  3. Root, TLD, and Authoritative Servers: The resolver may contact root servers, top-level domain (TLD) servers, and authoritative servers to resolve the name.
  4. Response: The IP address is returned to your device, which then connects to the website.

🛠️ Common DNS Commands​

nslookup           # Query DNS records for a domain
traceroute         # Trace the path packets take to a destination
dig                # Flexible DNS lookup utility
whois              # Lookup domain registration info
host               # Simple DNS lookup utility

🔒 Security Topics​

  • DNS over TLS: Encrypts DNS queries for privacy (Cloudflare guide)
  • DNS Cache Poisoning: Attack that corrupts DNS cache, redirecting traffic (Cloudflare guide)
  • DNS Spoofing: Faking DNS responses to redirect users (Wikipedia)
  • DNS Hijacking: Redirecting DNS queries to malicious servers (Wikipedia)

📚 Useful Links​

📝 Notes​

  • DNS is critical for internet usability and security.
  • Using secure DNS (like DNS over TLS or DNS over HTTPS) helps protect privacy.
  • Public DNS providers (Cloudflare 1.1.1.1, Google 8.8.8.8, Quad9) offer alternatives to ISP DNS.