Guides · updated 2026-07-05
DNS records explained: A, AAAA, CNAME, MX and TXT
The five record types that run practically every website and mailbox, in plain language, with what breaks when each is wrong.
A and AAAA — the address records
A maps a name to an IPv4 address; AAAA to IPv6. When your site is unreachable after a migration, a stale A record is the first suspect. Check them with any DNS lookup tool.
CNAME — the alias
CNAME points one name at another name (www at the bare domain, for example). A CNAME cannot coexist with other records for the same name — the classic cause of "why can’t I add MX at www".
MX — where mail goes
MX records name the servers that accept your email, with priorities. Wrong MX means silently vanishing mail: senders get no error, and you get no messages.
TXT — proofs and policies
TXT carries SPF, DKIM and DMARC (email authenticity), and ownership-verification strings for services like Google Workspace. Most deliverability problems end in a missing or malformed TXT record.
TTL — how fast changes travel
Every record carries a TTL: how long resolvers may cache it. Lower it before planned changes; restore it after. High TTL is why a DNS fix can seem to "not work" for hours.