A 记录
Maps a domain name to an IPv4 address.
A 记录是什么？
The A record is the workhorse of DNS. It tells resolvers which IPv4 address answers for a given hostname, so browsers, APIs and command-line tools can translate "example.com" into something like 93.184.216.34 and open a TCP/UDP socket to it.
区域文件示例
example.com. 300 IN A 93.184.216.34
常见用例
- ▸Point a web hostname (apex or subdomain) at a server.
- ▸Round-robin load balancing — set multiple A records with the same name.
- ▸Failover by lowering TTL ahead of a planned cutover.
- ▸Region-aware routing via GeoDNS providers.
常见坑
A records cannot be used at the apex if the host has a CNAME (RFC 1034 forbids it). Use an ALIAS / ANAME if your DNS provider supports it, or flatten the CNAME to A records.
相关记录类型
AAAA record
Maps a domain name to an IPv6 address.
CNAME record
Aliases one hostname to another — the resolver follows it transparently.
MX record
Tells the world which mail servers receive email for a domain.
CAA record
Certificate Authority Authorization — declares which CAs are allowed to issue certs for your domain.