IPv6 Readiness Check

IPv6 readiness check

Can this domain and its mail servers be reached over IPv6?

How this check works

The check looks up the domain's AAAA (IPv6) and A (IPv4) records for both the bare domain and www, then each mail server listed in its MX records, and its nameservers. It reports which of those can be reached over IPv6. All lookups go through public resolvers from your browser.

How to read the results

  • Website on IPv6: the domain or www has AAAA records, so IPv6-only and IPv6-preferring clients can connect directly. Most mobile networks now prefer IPv6.
  • Website IPv4 only: IPv6-only clients reach it through their provider's translation (NAT64), which works but adds a hop you don't control.
  • Mail servers on IPv6: if your MX hosts have AAAA records, other servers may deliver over IPv6. Then each IPv6 address needs its own PTR record that resolves back, or Gmail and others will reject or defer the mail. See reverse DNS for mail servers.
  • Nameservers on IPv6: lets IPv6-only resolvers query your zone directly.

Before you add AAAA records

An AAAA record is a promise that the service answers on that address. Clients try IPv6 first, and a broken IPv6 path shows up as slow or failed connections for some users. Make sure the server listens on IPv6, the firewall allows it, and the TLS certificate covers the name on both addresses. Then add the record with a short TTL so you can remove it quickly if needed.

Updated 26 October 2026

Related checks

  • Whois Search

    Who is this domain registered with, when does it expire, and is it locked?

  • Nameserver Lookup

    Which nameservers are authoritative for this domain, and which DNS provider runs them?

  • DNS Name Lookup

    What does DNS return for this name right now?

  • DNS Propagation Checker

    What does each public resolver return for this record right now?

FAQ

What does partial mean?

The domain is on IPv6 but some or all of its mail servers are not. Mail still arrives over IPv4; the gap matters when a sending server prefers IPv6 and the receiving host has no address for it.

Why check the www subdomain separately?

Plenty of sites publish AAAA records for the apex and forget www, or the other way round. Both names have to work for IPv6 clients to be served consistently.

Why does my IPv6 mail server need a PTR record?

Receivers use reverse DNS to decide whether a connection is legitimate. An IPv6 address with no PTR, or one whose name does not resolve back to the address, is treated like a missing identity and the mail is rejected or deferred.