AAAA Record
DNSAAAA Record is a DNS record type that maps a hostname to an IPv6 address, enabling clients to reach a server over the IPv6 network. When a domain has an AAAA record, resolvers can return the IPv6 destination alongside or instead of IPv4 results. It is essential for dual-stack deployments, modern connectivity, and ensuring your site remains reachable as IPv6 adoption grows.
How It Works
An AAAA record (pronounced “quad-A”) stores a 128-bit IPv6 address for a domain name, such as example.com or a subdomain like www.example.com. When a user visits the hostname, their device asks a recursive resolver for DNS records. If the resolver receives an AAAA record, it can return the IPv6 address so the client can connect to the server using IPv6 routing.
Most websites run in a dual-stack setup, publishing both an A record (IPv4) and an AAAA record (IPv6). Modern clients typically prefer IPv6 when it is available and working, but will fall back to IPv4 if IPv6 connectivity fails (behavior varies by operating system and network). Because of this, an incorrect AAAA record can cause slow connections or intermittent failures even if the A record is correct, especially when clients attempt IPv6 first.
Why It Matters for Web Hosting
When comparing hosting plans, AAAA record support matters if your host provides IPv6 addresses for your server, load balancer, or CDN endpoint. Publishing the right AAAA record can improve reachability for IPv6-only networks and reduce reliance on IPv4. It also affects troubleshooting: if a host advertises IPv6 but your DNS points to the wrong IPv6 address, visitors may see timeouts even though IPv4 appears fine.
Common Use Cases
- Enabling IPv6 access to a web server by mapping a hostname to its IPv6 address
- Dual-stack DNS setups that publish both A (IPv4) and AAAA (IPv6) for the same hostname
- Pointing subdomains (www, api, mail) to IPv6-capable services or reverse proxies
- Publishing IPv6 addresses for CDN, WAF, or load balancer front doors when provided by your hosting stack
- Supporting IPv6-only clients in certain mobile, ISP, or enterprise networks
AAAA Record vs A Record
Both records map names to IP addresses, but an A record returns an IPv4 address (32-bit), while an AAAA record returns an IPv6 address (128-bit). In hosting, you often use both so clients can connect over either protocol. If your hosting environment is not actually reachable via IPv6, it is usually better to omit the AAAA record than to publish an incorrect one, because many clients will try IPv6 first and only later fall back to IPv4.