AAAA Record (IPv6 Address Record)

What is an AAAA Record?

An AAAA record (pronounced "quad-A") is a DNS record type that maps a domain name to an IPv6 address. It's the IPv6 equivalent of the A record, which handles IPv4 addresses. The "AAAA" name comes from IPv6 addresses being four times longer than IPv4 addresses (128 bits vs 32 bits).

Why AAAA Records Matter

IPv4 addresses are running out. The 4.3 billion available IPv4 addresses seemed abundant in the 1980s but are now exhausted. IPv6 provides 340 undecillion addresses (3.4 × 10^38), ensuring the internet can continue growing.

IPv6 Adoption Statistics

• Major providers (Google, Facebook, Netflix) serve significant traffic over IPv6
• Many ISPs now provide IPv6 connectivity by default
• Mobile networks often prefer IPv6
• Cloud providers offer IPv6 support

AAAA Record Format

example.com.    IN    AAAA    2606:2800:220:1:248:1893:25c8:1946

IPv6 addresses are written as eight groups of four hexadecimal digits:

• Full form: 2606:2800:0220:0001:0248:1893:25c8:1946
• Compressed: 2606:2800:220:1:248:1893:25c8:1946 (leading zeros omitted)

Configuring AAAA Records

Basic Configuration

@       IN    AAAA    2001:db8::1
www     IN    AAAA    2001:db8::1

Dual-Stack Setup (IPv4 + IPv6)

Most websites should support both protocols:

example.com.    IN    A       203.0.113.50
example.com.    IN    AAAA    2001:db8::1
www             IN    A       203.0.113.50
www             IN    AAAA    2001:db8::1

Clients capable of IPv6 will prefer AAAA records; others fall back to A records.

How DNS Resolution Works with AAAA

Modern DNS resolvers query for both A and AAAA records:

1. Parallel Queries: Resolver sends A and AAAA queries simultaneously

2. Happy Eyeballs: Clients race IPv4 and IPv6 connections

3. Fastest Wins: The first successful connection is used

4. Fallback: If IPv6 fails, IPv4 is used automatically

This "Happy Eyeballs" algorithm (RFC 6555) ensures users get the fastest connection without noticing the protocol negotiation.

When to Add AAAA Records

You Should Add AAAA Records If:

• Your hosting provider offers IPv6 addresses
• Your CDN supports IPv6
• You want to future-proof your infrastructure
• You serve mobile users (many mobile networks prefer IPv6)

You Might Skip AAAA Records If:

• Your hosting only provides IPv4
• You're behind a load balancer without IPv6
• You need to simplify troubleshooting temporarily

Checking AAAA Records

dig example.com AAAA

; ANSWER SECTION:
example.com.    300    IN    AAAA    2606:2800:220:1:248:1893:25c8:1946

curl "https://domscan.net/v1/health?domain=example.com"
# Includes hasAAAA in DNS details

Common Issues

Missing AAAA Records

Sites without AAAA records may experience:

• Slower connections on IPv6-preferring networks
• Connectivity issues if IPv4 NAT is problematic
• Reduced performance for mobile users

Incorrect AAAA Records

Wrong IPv6 addresses cause connection failures for IPv6 users while IPv4 users remain unaffected—making issues hard to detect.

IPv6-Only Visitors

A small but growing population uses IPv6-only connections. Without AAAA records, your site is inaccessible to them.

Best Practices

1. Support dual-stack: Configure both A and AAAA records

2. Test IPv6 connectivity: Verify your server actually responds on IPv6

3. Monitor both protocols: Include IPv6 in your uptime monitoring

4. Use consistent TTLs: Match A and AAAA record TTLs

5. Update CDN settings: Enable IPv6 at your CDN if available

Adding AAAA records is increasingly important as IPv6 adoption grows and IPv4 exhaustion continues.