How is IPv6 support measured for the Registrar Scorecard?

How we go about it

As recently announced, we've added an IPv6 incentive to the Registrar Scorecard (RSC). If you missed it, you can still watch a Dutch-language webinar explaining all the ins and outs, or read an English summary of what was said. The RSC is a scheme that rewards registrars for helping to improve the quality of the .nl zone. Following the changes, that includes making domain names reachable using IPv6. The new incentive is part of our efforts to promote the new protocol. And it's prompted a number of people to ask just how we measure IPv6 support. Hence this article.

The details

Through the RSC, we reward registrars for making domain names reachable using IPv6. To decide whether a domain name is reachable, we look at the name server, web server and mail server. The IPv6 connectivity of each domain name is tested using tools developed by SIDN Labs.

How we go about it

First, we test the name servers for the domain name. That involves looking up the domain name in the Domain Name System (DNS) using IPv4. We then check whether those name servers can also be reached using IPv6. Version 6 connectivity has to be confirmed for at least two of them for the name to count towards the incentive.

Next, we test any mail server(s) linked to the domain name. For that, we only look at the MX records. If we find at least one mail server that can be reached within seven seconds using IPv6, the domain name counts towards the incentive. But not all domain names have MX records, of course. That's not a problem. However, if there are MX records, and the relevant mail server is reachable only using IPv4, the domain name is excluded from the incentive calculation.

Finally, we see whether there's a website linked to the domain name, which we can reach within seven seconds using IPv6. First we try 'www' with the domain name in question, e.g. ''. If we can't find an AAAA record in the DNS for that, or if we don't get an HTTP response when we use the AAAA record, we try the apex van the domain name, e.g. ''.

Name server Web server Mail server
IPv4 + IPv6 None IPv4 + IPv6
IPv4 + IPv6 IPv4 + IPv6 None
IPv4 + IPv6 IPv4 + IPv6 IPv4 + IPv6
IPv6 IPv6 IPv6

Useful to know

The basic principle is that anything that works with IPv4 needs to work with IPv6 as well for the name to count towards the incentive. To sum up, the incentive is payable in respect of domain names whose name servers and mail and/or web servers are reachable using IPv6.

Same content

Ideally, the same content should be available, whether the visitor uses IPv4 or IPv6. We've come across some cases where, for example, a normal website was reachable using IPv4, but only a parking page was found using IPv6. That's clearly unhelpful to the growing number of people trying to visit the domain using IPv6. In due course, therefore, we may start checking content as well. But we aren't doing that yet.

Bespoke reports and dashboard

Every registrar has access to a bespoke report, detailing our scan findings for each domain name in the registrar's portfolio. Account-specific information is also available from the RSC dashboard.We check the IPv6 status of every registrar's portfolio once a quarter. Each reward payment is calculated on the basis of the most recent scan. So July's payment is based on the June scan, and January's payment on the December scan. If you have any questions about the incentive, feel free to get in touch. We're always happy to help!


Added on the basis of questions and feedback from registrars:

  • Domain names that meet the IPv6 criteria, but are redirected to domain names that don't support IPv6, don't count towards the incentive.

  • To prevent looping, a limit applies to the number of redirects followed. If the limit is reached, the domain name does not count towards the incentive.

  • When testing web server connectivity, we don't check port 443. SSL isn't therefore relevant in this context.

  • Domain names that are reachable only using IPv6 do count towards the incentive.

  • has a tool for checking whether a domain name is reachable using IPv6.


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