IPv6 and the DNS root

The indefatigable Iljitsch van Beijnum published a story on ArsTechnica about IPv6 in the DNS root servers. For various technical reasons the root DNS servers have not listed their IPv6 addresses in the hints file, which is used by recursive nameservers. There was concern that old, broken DNS software and poorly configured firewalls would break if IPv6 addresses were added to the hints file.

In February, 2008, this will change; IANA will publish IPv6 addresses in the hints file. Initially, they will include IPv6 addresses for the F, H, K, and M servers. This means that it will be possible to do DNS entirely over IPv6, provided, of course, that all of the intermediate DNS servers are IPv6-accessible. This is a huge step for the IPv6 transition.

This got me thinking: How many of the top-level-domains have IPv6-accessible authoritative nameservers? I whipped up a quick Java program to check this. Answer: About two-thirds of them. (Sadly, .edu is not among them. Damnit, educause!) I was very surprised by this. IPv6 DNS is more prevalent than I had thought.

Here's the complete list: