Record types
- A / AAAA: the IPv4 / IPv6 address a name points to.
- CNAME: an alias; the name points to another name instead of an address.
- MX: the mail servers that receive email for the domain, with priority (lower = preferred).
- TXT: free text, used for SPF (
v=spf1), DMARC (on_dmarc.), DKIM keys and ownership verification. - NS: the authoritative name servers that host the domain's zone.
- SOA: zone metadata: primary server, admin contact, serial number and timers.
- CAA: which certificate authorities may issue TLS certificates for the domain.
Why a change is not visible yet
Resolvers keep each answer for its TTL (time to live, in seconds). After you edit a record, old answers can live in caches until their TTL expires; that delay is what people call "DNS propagation". Lowering the TTL a day before a planned change makes the switch faster.
Learn more in What is DNS.