DNS (Domain Name System)

The phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com.

Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

The Domain Name System (DNS) is a hierarchical, decentralized naming system that maps human-readable domain names (like example.com) to the numeric IP addresses (like 93.184.216.34) that computers use to identify each other on the network. DNS resolution involves a chain of queries through root servers, top-level domain servers, and authoritative name servers.

DNS record types serve different purposes. A records map domains to IPv4 addresses, AAAA records map to IPv6, CNAME records create aliases, and MX records direct email. TXT records store arbitrary text and are commonly used for domain verification and SPF/DKIM email authentication.

In API and serverless architectures, DNS is the entry point for all traffic. Custom domains for API endpoints require proper DNS configuration, often using CNAME records pointing to a gateway or CDN. DNS-based load balancing and geographic routing can direct API requests to the nearest edge location, reducing latency.