A Record vs AAAA Record: What Is the Difference?

If you are looking at DNS for web delivery, A and AAAA records are two of the most important lines in the zone.

They do similar jobs for different IP families.

The short version

• A record = hostname to IPv4
• AAAA record = hostname to IPv6

That is the cleanest possible distinction.

Why both can exist at the same time

A hostname can publish both:

• an IPv4 address with A
• an IPv6 address with AAAA

That is common on dual-stack services.

Why AAAA causes so much confusion

Because people often assume:

“if the site works on IPv4, adding IPv6 should be harmless.”

Not always.

If the AAAA path is broken, some users may still run into problems even though the IPv4 side looks fine.

That is why AAAA records deserve real checks, not just casual optimism.

When you need an A record

You need an A record whenever the hostname should resolve over IPv4.

That is still the default expectation in a lot of web setups.

When you need an AAAA record

You need an AAAA record when the hostname should resolve over IPv6.

The important part is that the actual service path needs to be healthy too. Publishing IPv6 in DNS without a working IPv6 delivery path is where trouble starts.

A practical workflow

If you are checking delivery:

1. inspect the A record
2. inspect the AAAA record
3. compare the visible infrastructure
4. test whether the destination behaves consistently

That is why How to Check A and AAAA Records for a Domain is a better operational page to keep open when you are troubleshooting.

Useful next reads

• How to Check A and AAAA Records for a Domain
• What Is My IPv6 Address and How Do I Check It?
• Why AAAA Records Break HTTP-01 Validation

The short version again

A and AAAA are not competing records. They are DNS answers for different IP families.

The trouble starts when one side is healthy and the other only looks healthy on paper.