Digital Lexicon Hub

The hierarchical, distributed naming system that translates domain names into IP addresses and other records used by web and email services.

DNS controls where a website, email and subdomains point, so errors or a lapsed domain can take sites offline or break email delivery; access to the DNS provider deserves the same protection as a bank account.

Before moving a site to a new host, a team lowers the A record TTL from 86,400 to 300 seconds two days ahead, switches the record, and adds SPF, DKIM and DMARC TXT records for the new email platform in the same zone.

Changes are not instant because resolvers cache records until the TTL expires. Plain DNS answers are not authenticated unless DNSSEC is used, and hijacked registrar or DNS accounts can redirect web traffic and email.

Names form a tree of labels administered in zones. A recursive resolver answers a lookup by querying root, top-level domain and then authoritative nameservers, caching each answer for its time-to-live. Resource records include A and AAAA for addresses, CNAME for aliases, MX for mail, NS for delegation and TXT for data such as Sender Policy Framework (SPF) and DMARC policies. The core concepts are defined in RFC 1034, with implementation details in RFC 1035.