IPv6 Support Checker

About IPv6 support checker

IPv6 Support Checker audits whether a domain works over IPv6 in three separate places: the website, the mail servers and the nameservers. Each is scored on its own, because a domain can publish an AAAA record for its website while its mail or DNS remains IPv4-only.

How to use it

1. Enter the domain, such as example.com, in the Domain box.
2. Press Check IPv6. Our server looks up the address, mail exchanger and nameserver records and their IPv6 addresses.
3. Read the banner for the overall score out of 3 and the one-line summary.
4. Go through Readiness checks. Each has a Pass or Missing badge, a detail line and a How to fix note.
5. Consult the AAAA records, Mail hosts and Nameservers tables for the addresses found.

A partly ready domain

No AAAA on the site, one MX host with no IPv6, one nameserver with an IPv6 address

Partial IPv6 support (1 of 3). Missing: website aaaa records, mail hosts over ipv6.

When to use it

• Checking readiness before a customer or regulator requires IPv6 reachability.
• Finding that mail servers are the only part of a stack still stuck on IPv4.
• Confirming a DNS provider offers IPv6 glue for the domain's nameservers.
• Verifying that enabling IPv6 on a CDN published the expected AAAA record.

Questions about IPv6 support checker

Does it connect to the site over IPv6?

No. It checks that the DNS records exist, not that a connection succeeds. A published AAAA record pointing at a server that is not listening would still pass, so follow up with a real connection test.

Why does a domain with no MX pass the mail check?

With no mail exchangers there is no mail service that could lack IPv6, so penalizing it would be misleading. The detail line says that no MX records were found.

What is IPv6 glue?

AAAA records for nameserver hostnames. Without at least one, a client that has only IPv6 connectivity cannot reach the zone's DNS, and so cannot resolve the domain at all.

Are all nameservers and mail hosts examined?

Up to eight of each are checked, which covers virtually every real setup. The domain is sent to our server, and up to 10 checks per minute are allowed.

What counts as ready?

All three checks passing. Two out of three is treated as partial and the missing area is named in the summary.

Related tools

• DNS LookupLook up DNS records for a domain
• DNS propagation checkerQuery a domain's DNS records across four public resolvers and see whether they agree.
• Subnet calculatorCalculate network, broadcast, host range, and subnet splits for any IPv4 or IPv6 CIDR block.
• IP LookupLook up information about an IP address
• WHOIS LookupLook up WHOIS information for a domain
• PingPing a domain or IP address