There are over 80 RFC-defined DNS record types. In practice, ten of them cover everything a normal site uses. Here's the working set.
The everyday records
- A — IPv4 address for a hostname.
- AAAA — IPv6 address for a hostname.
- CNAME — alias for another hostname. Can't coexist with other records at the same name.
- MX — mail server for the domain.
- TXT — arbitrary text. Used for SPF, DMARC, domain verification.
- NS — nameservers authoritative for the domain.
- SOA — "start of authority" metadata: primary NS, admin email, serial, refresh intervals.
- CAA — which CAs are allowed to issue certs for this domain.
- SRV — service location (used by SIP, XMPP, Minecraft).
- PTR — reverse DNS, hostname for an IP.
All ten are visible at once via DNS Lookup.