example.com. 3600 IN A 93.184.215.14
An A record (address record) connects a hostname to a 32-bit IPv4 address. When a browser opens example.com, its resolver asks for the A record (and the AAAA record for IPv6) and connects to the address it receives.
Format
Each A record has a name, a TTL in seconds, the class IN and one IPv4 address. A name can have several A records; resolvers return all of them, and clients usually try them in order — a simple form of load distribution and redundancy.
A records and the apex
The bare domain (example.com, the “apex”) must use A/AAAA records, because a CNAME is not allowed next to the SOA and NS records that live there. Many DNS providers offer “ALIAS” or “flattened CNAME” features that look up a target name and publish the result as A records.
TTL and changes
Resolvers cache an answer for its TTL. Before migrating a site, lower the TTL (for example to 300 seconds) a day in advance so the new address takes effect quickly; raise it again afterwards.
Frequently asked questions
- Can a domain have multiple A records?
- Yes. All addresses are returned and clients pick one, which spreads load and allows failover to another address.
- What is the difference between an A and an AAAA record?
- An A record holds an IPv4 address; an AAAA record holds an IPv6 address. Dual-stack sites publish both.
- Can an A record point to another domain?
- No, only to an IPv4 address. To point a name at another name, use a CNAME (not allowed at the apex).