AAAA record
The DNS record that maps a host name to an IPv6 address, the IPv6 counterpart of the A record.
What it means
AAAA records (RFC 3596) hold 128-bit IPv6 addresses. If a mail server has an AAAA record and IPv6 connectivity, other servers may deliver to it over IPv6, and it may send over IPv6 itself.
That second part catches people out. A server that starts sending over IPv6 needs its IPv6 address covered too: an ip6 entry (or an a/mx mechanism) in SPF, and a PTR record for the IPv6 address whose name resolves back through AAAA. Gmail rejects IPv6 mail that lacks PTR records or authentication.
Check both A and AAAA results when testing a host.
Example
mx1.example.com. 3600 IN AAAA 2001:db8::25Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- RFC 3596: DNS Extensions to Support IP Version 6, section 2rfc-editor.org
- Google: Email sender guidelinessupport.google.com
All 432 terms in the glossaryThe wiki: blocklists and bounce codes