An AAAA record (pronounced "quad-A") is a DNS record that maps a domain name to an IPv6 address. It is the IPv6 equivalent of the A record, which maps to IPv4 addresses. The four As reflect the fact that IPv6 addresses are 128-bit — four times the size of 32-bit IPv4 addresses.
What an AAAA Record Looks Like
example.com. 3600 IN AAAA 2606:4700:3033::6815:2155Why IPv6 and AAAA Records Matter
The pool of available IPv4 addresses was exhausted in 2011. IPv6 provides a vastly larger address space (340 undecillion addresses), ensuring the internet can continue to grow. Major ISPs, mobile networks and cloud providers have rolled out IPv6 extensively.
Dual Stack
Best practice is to publish both A and AAAA records for your domain. This is called a dual-stack configuration:
- Clients with IPv6 connectivity prefer the AAAA record.
- Clients on IPv4-only networks use the A record.
- Browser's "Happy Eyeballs" algorithm tries both simultaneously and uses whichever connects first.
Checking AAAA Records
Use the DNS Lookup tool and select "AAAA" to see whether a domain has IPv6 configured.