# DNS

> Domain Name System — the lookup that turns dfieldsolutions.com into a server address; when it breaks, everything looks broken.

Every visit starts with a phone-book lookup: the browser asks a resolver, the resolver asks the authoritative nameserver, the answer — an IP — is cached along the way for the record's TTL. It is invisible until it is not: 'site down' is very often 'DNS down' or 'DNS propagating'.

The records a business site actually manages: A/AAAA (the server), CNAME (aliases like www), MX (who gets the email), TXT (SPF, DKIM, verification tokens — email deliverability and domain ownership live here). Changing them is instant to save and slow to spread, because every resolver on earth cached the old answer.

## Related terms

- https://dfieldsolutions.com/en/glossary/cdn.md
- https://dfieldsolutions.com/en/glossary/tls.md
- https://dfieldsolutions.com/en/glossary/indexing.md

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Source: https://dfieldsolutions.com/en/glossary/dns
DField Solutions — Dunakeszi, Hungary — dezso@dfieldsolutions.com
Booking: see https://dfieldsolutions.com/en/contact