Guide
DNS foundations
DNS turns names people remember into destinations computers can use. Reliable management starts with understanding which system is authoritative and what each record controls.
Zones and authority
A DNS zone is the managed record set for a domain. Its registrar delegates authority to nameservers through NS records. Changes made anywhere else have no public effect, so always confirm the delegated nameservers before editing records.
Common record types
- A and AAAA connect a name to IPv4 or IPv6 addresses.
- CNAME aliases one hostname to another and normally cannot coexist with other data at the same name.
- MX selects mail servers and uses a numeric priority.
- TXT carries verification and email-policy text.
- CAA limits which certificate authorities may issue certificates.
Apex and wildcard names
Many control panels display @ for the zone apex and * for a wildcard. For example.com, these publish as example.com. and *.example.com.. A wildcard answers only when a more specific record does not exist.
TTL and caching
TTL tells recursive resolvers how long an answer may be cached. Lower it before a planned migration, wait for the previous value to expire, then make the change. Raising it afterward reduces repeated lookups.