AAAA Record Explained: IPv6 DNS Records
Publish and verify IPv6 address records, and check connectivity before directing website visitors to an IPv6 endpoint.
The named scenario below is a worked example for learning, not a verified incident report. Provider settings and outcomes vary.
AAAA Record (IPv6) Resolution
Request AAAA record
Resolver queries NS
Returns IPv6 address
2001:db8::1
Browser connects via IPv6
Content delivered
🎯 Illustrative example: Gaurav Adds IPv6 Support to His Website
Gaurav's hosting now supports IPv6. He adds an AAAA record alongside his existing A record:
Current setup: A record only
gaurav.com → A → 93.184.216.34 (IPv4 only). IPv6 users connect via IPv4 fallback.
Adds AAAA record
gaurav.com → AAAA → 2606:2800:220:1:248:1893:25c8:1946 (IPv6 address from hosting provider).
IPv6-native clients use AAAA
Mobile networks (Jio, T-Mobile) are largely IPv6. These users now connect directly via IPv6 — faster!
IPv4 clients use A record
Older networks still use the A record. Both coexist — dual-stack setup.
Gotcha: IPv6 must be configured on server
Server must actually listen on the IPv6 address. AAAA record without server config = connection refused.
Dual-stack works perfectly
All users can connect. IPv6 users get slightly faster connections. No IPv4 users are affected.
Dual-stack (A + AAAA) gives the best compatibility — IPv4 and IPv6 users both connect.
Adding AAAA without configuring IPv6 on the server = broken connections for IPv6 users.
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 serves the same purpose as an A record but for the newer, 128-bit IPv6 address format instead of the 32-bit IPv4 format.
example.com. IN AAAA 2606:2800:0220:0001:0248:1893:25c8:1946
A Record vs AAAA Record
| Feature | A Record | AAAA Record |
|---|---|---|
| IP Version | IPv4 | IPv6 |
| Address Length | 32 bits (4 octets) | 128 bits (8 groups of 4 hex digits) |
| Example | 93.184.216.34 | 2606:2800:220:1:248:1893:25c8:1946 |
| Address Space | ~4.3 billion | ~340 undecillion |
| Adoption | Universal | Growing (~40% globally) |
Both record types can coexist for the same domain. This is called dual-stack — clients that support IPv6 use the AAAA record, while IPv4-only clients use the A record.
Why IPv6 and AAAA Records Matter
- IPv4 exhaustion — All IPv4 addresses have been allocated; IPv6 provides virtually unlimited addresses
- Performance — Many mobile carriers and ISPs now prefer IPv6, potentially reducing latency
- Future-proofing — IPv6 adoption is growing; major CDNs and cloud providers fully support it
- SEO benefit — Google has stated IPv6 support is a positive signal for crawling
How to Set Up an AAAA Record
- Get your server's IPv6 address — Check your hosting provider's dashboard or run
ip -6 addr show - Log in to your DNS provider and navigate to DNS management
- Add a new AAAA record with the hostname and IPv6 address
- Verify with:
dig example.com AAAA +short
Tip: Use mydnsreport.com DNS Lookup to verify your AAAA record is resolving correctly.
How DNS Resolution Works with AAAA Records
When a client connects to a domain, the resolver queries for both A and AAAA records. Modern systems use the Happy Eyeballs algorithm (RFC 8305):
- Query for both A and AAAA records simultaneously
- Prefer IPv6 (AAAA) but start an IPv4 fallback after a short delay (~250ms)
- Use whichever connection succeeds first
This ensures IPv6 is preferred without penalizing users if IPv6 connectivity is broken.
Common Mistakes
- • Adding AAAA without IPv6 connectivity — If your server doesn't actually accept IPv6 traffic, clients may experience delays
- • Forgetting reverse DNS (PTR) — If you add AAAA records for a mail server, also set up IPv6 PTR records
- • Firewall not allowing IPv6 — Ensure your firewall rules apply to both IPv4 and IPv6
Frequently Asked Questions
What is an AAAA record?
An AAAA record maps a domain name to an IPv6 address, just like an A record maps to an IPv4 address.
What is the difference between an A record and an AAAA record?
An A record points to an IPv4 address (32-bit) while an AAAA record points to an IPv6 address (128-bit). Both can exist for the same domain.
Do I need an AAAA record?
If your server supports IPv6, adding an AAAA record improves accessibility and can improve performance for IPv6-capable clients. It's increasingly recommended.