We’ve just given our IPv6 Health Check a significant overhaul.

IPv6 is coming, and there’s a lot more to being ready for it than adding an AAAA record and enabling IPv6 on your web server. Google are often cited as an example of an IPv6-enabled website, but the truth is, in an IPv6-only world, nobody would ever find Google because none of their nameservers have IPv6 addresses:

Our IPv6 Health Check aims to reach the parts that other testers don’t reach to find out if your domain is really ready for IPv6. Do your mail servers have IPv6 addresses? Do they have reverse DNS for those addresses? Do your SPF records include IPv6 addresses?

The latest version of our health check includes an experimental IPv6 nameserver delegation and glue test that checks that all nameservers the delegation chain between the root DNS servers and your zone have IPv6 addresses, and sufficient glue to allow you to find them in an IPv6-only world. This test has already uncovered some interesting anomalies which we’ll dig into further in a future post.