AAAA Record

An AAAA record (pronounced "quad-A") does the same job as an A record but for IPv6. Instead of mapping to a 32-bit IPv4 address like 93.184.216.34, it maps to a 128-bit IPv6 address like 2606:2800:220:1:248:1893:25c8:1946.

The name comes from the fact that IPv6 addresses are four times longer than IPv4 addresses. An A record holds 4 bytes, an AAAA record holds 16 bytes. Hence quad-A.

For CDNs, AAAA records matter because a growing chunk of internet traffic is IPv6. Mobile carriers in particular have pushed IPv6 adoption hard. T-Mobile US routes over 90% of traffic over IPv6. India's Jio network is predominantly IPv6. If your CDN doesn't serve AAAA records, these users either fall back to IPv4 through carrier-grade NAT (adding latency) or in rare cases can't reach you at all.

Dual-stack is the standard approach: publish both A and AAAA records for the same hostname. The client's operating system uses Happy Eyeballs (RFC 8305) to race IPv4 and IPv6 connections and pick the winner. In practice, IPv6 often wins because it avoids NAT traversal overhead.

Most major CDNs (Cloudflare, Fastly, Akamai, CloudFront) support dual-stack out of the box. When you onboard a domain, they publish both record types automatically. Cloudflare even has a "pseudo IPv4" feature that maps IPv6-only visitors to IPv4 addresses for backends that don't support IPv6.

One gotcha: if your origin only supports IPv4, make sure your CDN handles the protocol translation. The edge connects to users over IPv6 while talking to your origin over IPv4. Most CDNs handle this transparently, but verify it during setup.

When debugging, always check both A and AAAA records. A DNS issue might only affect one protocol. Use dig with the AAAA type to query specifically for IPv6 records.