AAAA Records and IPv6: Future-Proofing Your Domain's DNS
IPv4 addresses have been exhausted for over a decade, yet many domains still lack IPv6 support. AAAA records are the DNS mechanism that maps your domain to an IPv6 address. This guide explains what AAAA records are, why IPv6 adoption matters, and how to set up dual-stack DNS so your domain works seamlessly on both protocols.
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 is the IPv6 equivalent of the A record, which maps a domain to an IPv4 address. The name "AAAA" reflects the fact that IPv6 addresses are four times the length of IPv4 addresses — 128 bits versus 32 bits.
An IPv4 A record looks like this:
example.com. IN A 93.184.216.34An IPv6 AAAA record looks like this:
example.com. IN AAAA 2606:2800:220:1:248:1893:25c8:1946When a client (browser, email server, API client) wants to connect to your domain, the DNS resolver queries for both A and AAAA records. If the client supports IPv6 and an AAAA record exists, it can connect directly over IPv6 without needing NAT traversal or other IPv4 workarounds. You can check your current AAAA records using our AAAA Lookup tool.
IPv4 vs IPv6: Why the Transition Matters
IPv4 provides approximately 4.3 billion unique addresses. That sounded like plenty in 1981 when the protocol was designed, but the explosion of internet-connected devices exhausted the global IPv4 pool years ago. Regional Internet Registries (RIRs) have been running on recycled and transferred address blocks since the early 2010s.
IPv6 solves this with a 128-bit address space, providing approximately 3.4 × 1038 unique addresses — enough for every grain of sand on Earth to have trillions of addresses. Beyond the larger address space, IPv6 offers several technical advantages:
- No NAT required. Every device can have a globally unique address, simplifying end-to-end connectivity and reducing latency from NAT translation.
- Simplified header format. IPv6 headers are fixed-length and more efficient for routers to process, improving forwarding performance.
- Built-in IPsec support. IPv6 was designed with security in mind, with IPsec as a fundamental component rather than an add-on.
- Better multicast and anycast. IPv6 has native support for multicast, replacing the broadcast mechanism in IPv4, and improved anycast for load distribution.
- Autoconfiguration (SLAAC). Devices can automatically configure their own IPv6 addresses without DHCP, using Stateless Address Autoconfiguration.
How AAAA Records Fit Into DNS Resolution
When a client application resolves a domain name, the operating system's DNS resolver typically sends two parallel queries: one for the A record (IPv4) and one for the AAAA record (IPv6). This behavior is controlled by the Happy Eyeballs algorithm (RFC 8305), which determines how clients choose between IPv4 and IPv6 connections.
The Happy Eyeballs algorithm works by initiating connection attempts on both protocols simultaneously, with a slight preference for IPv6. If the IPv6 connection is established within a short timeout window (typically 250ms), it is used. Otherwise, the client falls back to IPv4. This means that adding AAAA records to your domain will never break IPv4 connectivity — clients that cannot use IPv6 simply use the A record instead.
You can verify whether your domain returns both A and AAAA records using our DNS Lookup tool, which queries all record types for a given domain.
Setting Up AAAA Records: Step-by-Step
Before adding AAAA records, you need to ensure your hosting provider or server supports IPv6. Most major cloud providers (AWS, Google Cloud, Azure, DigitalOcean, Vercel, Cloudflare) assign IPv6 addresses by default. Here is how to add AAAA records:
- Find your server's IPv6 address. Check your hosting provider's dashboard or run
ip -6 addr showon your server. - Log into your DNS provider. Navigate to the DNS management panel for your domain.
- Add an AAAA record. Set the name (e.g.,
@for root or a subdomain), type to AAAA, and the value to your IPv6 address. - Set an appropriate TTL. A TTL of 300–3600 seconds is typical. Lower values allow faster propagation of changes.
- Verify propagation. Use our DNS Propagation Checker to confirm the record has propagated to DNS servers worldwide.
Dual-Stack DNS Configuration
A dual-stack configuration means your domain has both A records (IPv4) and AAAA records (IPv6) published simultaneously. This is the recommended approach for the foreseeable future, as not all clients and networks support IPv6 yet.
; Dual-stack DNS configuration
example.com. IN A 93.184.216.34
example.com. IN AAAA 2606:2800:220:1:248:1893:25c8:1946
; Subdomains should also have both
www.example.com. IN A 93.184.216.34
www.example.com. IN AAAA 2606:2800:220:1:248:1893:25c8:1946
; Mail servers need IPv6 too
mail.example.com. IN A 93.184.216.35
mail.example.com. IN AAAA 2606:2800:220:1:248:1893:25c8:1947When setting up dual-stack for email servers, ensure that your mail server's reverse DNS (PTR record) is configured for both the IPv4 and IPv6 addresses. Many receiving mail servers check PTR records as part of spam filtering, and a missing reverse DNS entry on your IPv6 address can cause delivery issues.
Checking Your IPv6 Support
There are several ways to verify that your domain is properly configured for IPv6:
- AAAA Lookup — Query AAAA records for any domain to see its IPv6 addresses.
- DNS Lookup — View all DNS record types including A and AAAA side by side.
- DNS Propagation Checker — Verify that your AAAA records have propagated to DNS resolvers worldwide.
You can also test from the command line using dig AAAA example.com or nslookup -type=AAAA example.com.
Common IPv6 and AAAA Record Issues
While adding AAAA records is straightforward, several issues can arise:
- AAAA record without working IPv6. Publishing an AAAA record when your server does not actually have IPv6 connectivity causes timeouts for IPv6-capable clients before they fall back to IPv4. Always verify connectivity before adding the record.
- Missing reverse DNS for IPv6. If your mail server has an AAAA record but no corresponding PTR record for the IPv6 address, receiving servers may reject or flag your email as spam.
- Firewall blocking IPv6. Some firewalls are configured only for IPv4 traffic. Ensure your firewall rules include IPv6 (ip6tables on Linux) and allow traffic on the same ports as IPv4.
- CDN or proxy not passing IPv6. If you use a CDN or reverse proxy, ensure it supports IPv6 on both the frontend (client-facing) and backend (origin) connections.
- SPF and IPv6. If your mail server sends from an IPv6 address, your SPF record must include the IPv6 address using the
ip6:mechanism. Otherwise, SPF checks will fail for mail sent over IPv6.
IPv6 Adoption in 2026
Global IPv6 adoption has surpassed 45% of internet traffic as of 2026. Major networks including Comcast, T-Mobile, and Reliance Jio route the majority of their traffic over IPv6. Google reports that over 50% of its traffic comes from IPv6-capable clients. Cloud providers now assign IPv6 addresses by default on new instances.
For email specifically, IPv6 support is increasingly important. Gmail, Outlook, and Yahoo all accept email over IPv6 connections, and some providers give a slight deliverability advantage to properly configured IPv6 mail servers with valid PTR records and authentication (SPF, DKIM, DMARC).
If you have not yet added AAAA records to your domain, now is the time. The dual-stack approach ensures backward compatibility while future-proofing your infrastructure for the inevitable completion of the IPv6 transition.