What each does.
A RECORD
Points a name at an IPv4 address. Your main website record.
AAAA RECORD
The same for IPv6.
CNAME
Points a name at another name. Cannot coexist with other records for the same name.
Cloudflare supports CNAME at the root domain, which most providers do not. Useful in some configurations.
MX
Directs mail. Cannot be proxied. Points at a hostname, not an address.
TXT
Arbitrary text. Used for SPF, DKIM, DMARC and domain verification.
Frequently the records that go missing during a Cloudflare migration.
SRV
Service records, used by some applications.
CAA
States which certificate authorities may issue for your domain. If present and wrong, AutoSSL fails.
NS
Delegates a subdomain to different nameservers.
WHICH YOU ACTUALLY NEED
A record for the domain and www, MX records, and TXT records for SPF and DKIM.
Everything else is situational.
