DNS 记录类型 — 实用参考
常见 DNS 记录类型逐一讲解：作用、格式、使用场景，以及把生产搞砸的常见错误。
A
Maps a domain name to an IPv4 address.
AAAA
Maps a domain name to an IPv6 address.
MX
Tells the world which mail servers receive email for a domain.
NS
Lists the authoritative name servers for a zone.
TXT
Stores arbitrary text — most often SPF, DKIM, DMARC and ownership-verification tokens.
CNAME
Aliases one hostname to another — the resolver follows it transparently.
SOA
Start of Authority — metadata about the zone, including serial, refresh, retry and minimum TTL.
PTR
Reverse DNS — maps an IP back to a hostname.
SRV
Service-location record — specifies host AND port for a named service.
CAA
Certificate Authority Authorization — declares which CAs are allowed to issue certs for your domain.