An AAAA record (quad-A) is a DNS resource record that maps a domain name to an IPv6 address. While the standard A record handles 32-bit IPv4 addresses, the AAAA record stores a 128-bit address, accommodating the significantly larger address space of the IPv6 protocol.
When a client requests a domain, the DNS resolver looks for an AAAA record if the network environment supports IPv6. The server returns the address in hexadecimal format. This mechanism enables end-to-end connectivity without the need for Network Address Translation (NAT), reducing header overhead and routing complexity.
These records are essential for IPv6-only environments and Dual Stack configurations. Most modern operating systems and browsers prioritize AAAA records over A records using the Happy Eyeballs algorithm (RFC 8305) to ensure the fastest possible connection for the user.
Example
A typical entry in a zone file follows this format: example.com. IN AAAA 2001:0db8:85a3:0000:0000:8a2e:0370:7334. It includes the hostname, class (IN), type (AAAA), and the address. The TTL (Time to Live) value determines how long the record is cached by resolvers, typically ranging from 1 to 24 hours.