A vs AAAA Records: What's the Difference?
By Nathan Cole, Security Researcher · Updated 2026-06-02Part of our guide to DNS Records Explained: A Complete Guide to Every Record Type.
What's the Difference Between an A and AAAA Record?
Here is the short answer. An A record maps a domain name to an IPv4 address, while an AAAA record maps a domain name to an IPv6 address. Both do the same job: they point a hostname like example.com at the numeric address of the server that answers for it. What separates them is the version of the Internet Protocol the address uses. A record was defined in the original DNS specification, RFC 1035, and when a browser looks up your domain, it asks for an A record to connect over IPv4 and an AAAA record to connect over IPv6.
Both records are core building blocks of DNS. Want the bigger picture of how they fit alongside MX, TXT, CNAME, and other record types? Start with our pillar guide, DNS records explained. This article zooms in on the A versus AAAA distinction.
IPv4 vs IPv6 Address Formats
IPv4 addresses are 32 bits long, written as four decimal numbers separated by dots, each ranging from 0 to 255. A typical A record value looks like this:
93.184.216.34
IPv6 addresses are 128 bits long and written as eight groups of four hexadecimal digits separated by colons. The AAAA record type that carries them is specified in RFC 3596. A typical AAAA value looks like this:
2606:2800:220:1:248:1893:25c8:1946
IPv6 addresses are often shortened by collapsing consecutive groups of zeros into a double colon, so 2001:0db8:0000:0000:0000:0000:0000:0001 can be written 2001:db8::1. That huge address space is the reason IPv6 exists at all: IPv4 has roughly 4.3 billion addresses, which the world has effectively exhausted.
Why "AAAA"?
The name is not random. An IPv4 address is 32 bits, the size of a single A record. An IPv6 address is 128 bits, which is four times larger (4 × 32 = 128). Because it takes four "A's" worth of address space, the record type was named AAAA, pronounced "quad-A." It is a neat mnemonic that also happens to be technically literal.
A vs AAAA at a Glance
| Property | A Record | AAAA Record |
|---|---|---|
| IP version | IPv4 | IPv6 |
| Address size | 32 bits | 128 bits |
| Format | Dotted decimal | Colon-separated hex |
| Example | 93.184.216.34 | 2606:2800:220:1:248:1893:25c8:1946 |
| When used | IPv4 connections | IPv6 connections |
Running Both: Dual-Stack
Most well-configured domains publish both an A and an AAAA record. The setup is known as dual-stack: the server listens on both an IPv4 and an IPv6 address, and DNS advertises both. A connecting client then picks whichever protocol its network supports, often preferring IPv6 where it is available. You get the broadest reach without forcing visitors onto a single protocol.
The two records are independent of each other. Adding one does not affect the other, and removing your AAAA record will not break IPv4 visitors. Weighing A records against alias-style records? See CNAME vs A records for how those differ.
Multiple A Records and Round-Robin
A single hostname can carry several A records, each pointing to a different IPv4 address. When a resolver returns them, it typically rotates the order on each request. This is called round-robin DNS, and it spreads incoming connections across multiple servers, giving you a simple form of load balancing and redundancy. The same technique works with multiple AAAA records for IPv6.
Round-robin is not a true load balancer. It checks no server health and weighs no capacity. Still, it is an easy way to distribute traffic, and many sites pair round-robin DNS with a dedicated load balancer for finer control.
A Note on TTL
Every A and AAAA record carries a TTL (time to live), measured in seconds, that tells resolvers how long to cache the answer before asking again. A low TTL such as 300 seconds means changes propagate quickly but generates more lookups; a high TTL such as 86400 reduces query load but slows down changes. When you plan to migrate a server, lower the TTL ahead of time so the new address takes effect sooner.
How to Verify Your A and AAAA Records
The quickest way to confirm what a domain is actually publishing is to look it up. Our domain intelligence tool resolves A, AAAA, and every other record type in one pass and flags whether a domain is IPv4-only or fully dual-stack. For a step-by-step walkthrough of the underlying methods, read how to check DNS records.
Check Your Records Now
Want to see your domain's A and AAAA records instantly? Run a free DNS check and get a full breakdown of your IPv4 and IPv6 configuration in seconds.
Frequently asked questions
Do I need both A and AAAA records?
You do not strictly need both, but publishing both is recommended. An A record makes your domain reachable over IPv4 and an AAAA record makes it reachable over IPv6. Adding both is called dual-stack and ensures every visitor can connect using whichever protocol their network supports. If your server has an IPv6 address, adding an AAAA record is good future-proofing.
What happens if I only have an A record?
Your domain still works for the vast majority of visitors, because IPv4 remains the most widely supported protocol. Clients on IPv6-only networks may have to rely on a translation layer such as NAT64, which can add latency. You will not break anything by having only an A record, but IPv6 visitors connect more directly when an AAAA record is also present.
Can a domain have multiple A records?
Yes. A domain can have several A records, each pointing to a different IPv4 address. DNS resolvers return them in rotating order, a technique called round-robin DNS, which spreads traffic across multiple servers for basic load balancing and redundancy. The same applies to AAAA records for IPv6 addresses.