Definition
The Domain Name System (DNS) is a hierarchical, decentralized naming system that translates human-readable hostnames (like example.com) into numeric IP addresses.
Why It Matters
DNS functions as the “phone book” of the internet, making it human-navigable; without it, users would have to memorize long IP addresses for every website.
Core Concepts
- Hostname to IP Mapping: Translates domain labels to IPv4/IPv6 addresses that routers use to deliver data packet requests.
- DNS Resolution: The recursive query process where a resolver checks root servers, TLD servers, and authoritative name servers to find the IP.
- Caching: Resolvers and operating systems store DNS records locally for a Time To Live (TTL) period to speed up repeat requests.