Verisign has been offering IPv6 connections to their EPP servers for the last year. However as of March 14th the Verisign registry backend will become dual stacked ie. the hostnames for IPv4 and IPv6 connections will be identical.
While this may not impact that many registrars now, it will become more important over time, though it’s not clear if any registrars are currently connecting to the Verisign EPP servers over IPv6
As Verisign remind registrars, “It is important to note that client operating systems that are dual stacked (IPv4 and IPv6), may have a preference for communicating over IPv6 if the returned DNS records present both A and AAAA records“- in other words, if you have IPv6 make sure that you let Verisign know your IP range!