IPv6 transition: Observations from a name server perspective

By Dr. Burt Kaliski, Verisign chief technology officer, Network World |  Networking, IPv6

Now, if a name server is IPv6-enabled, requesters can send queries over either IPv4 or IPv6. In addition, the associated information can include either an IPv4 address or an IPv6 address (a so-called "AAAA" or "quad-A" record -- four times as many bits). The two choices are orthogonal, so overall there are four times as many options as before. This initial complexity is just the starting point, however, because of the recursive nature of DNS, which may result in transactions with additional name servers, some of which may be IPv6-enabled, and some not, in the search for an ultimate IPv4 or IPv6 address.

Operators of the authoritative name servers for large top-level domains (TLDs) have a privileged "observation point" for the transition from IPv4 to IPv6, relative to the "zone" or set of domain names for which the name server is authoritative. Verisign has been studying trends in the zones it operates name servers for -- including the DNS root, .com and .net, such as:

• The percentage of domain names in a given zone that are served by an IPv6-enabled name server (vs. IPv4-only).

• The percentage of DNS queries received via the IPv6 protocol (vs. IPv4).

• The percentage of DNS queries that request a quad-A record (vs. an A record).

Already, there has been a steady increase in the percentage of DNS queries over the IPv6 protocol at the two root name servers that Verisign operates. Labeled "A root" and "J root," these are two of the 13 name servers that requesters can contact to get the IP addresses of name servers for top-level domains. From May 2011 to May 2012, the percentage of queries to the A and J root name servers received over IPv6 has tripled, from just over 1% to between 3% and 4%. (This current rate is consistent with what we're aware of for other root name servers.) The percentage of queries over IPv6 to the name servers for .com and .net is still steady at just under 1%. Occasional fluctuations can be due to trial deployments of IPv6 at various parts of the Internet, or other variations in the mix of IPv4 vs. IPv6 traffic.

The steady increase is encouraging, because it means that more and more requesters are starting the hierarchical process of "resolving" a domain name into an IP address with an IPv6 communication to a root server. In a typical DNS deployment, the requesters are recursive name servers, acting on behalf of end-consumers that ultimately interact with the named resources. The increase reflects IPv6 adoption by recursive name servers and the networks they reach the root servers through. It doesn't necessarily mean that the named resource, the end-consumer, nor the networks they connect through support IPv6, though such transitions would be likely to follow, if not already in place.


Originally published on Network World |  Click here to read the original story.
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