DNS • Networking
DNS Deep Dive: How Domain Resolution Really Works Behind the Scenes
DNS translates human-friendly domains into IP addresses. Understanding the lookup chain helps debug resolution issues and optimize DNS for performance and security.
Lookup flow
- Client asks recursive resolver (ISP or public resolver).
- Resolver queries root servers for the TLD (e.g., .com).
- Resolver asks the TLD server for the authoritative nameserver for the domain.
- Resolver queries the authoritative server and returns the answer to the client.
Common record types
- A/AAAA – IPv4/IPv6 addresses
- CNAME – alias to another domain
- MX – mail exchange servers
- TXT – arbitrary text (SPF, DMARC)
DNS performance & security
Use low TTLs for dynamic services, CDN-backed DNS for global performance, and DNSSEC to protect against cache poisoning.
