The old Internet protocols, that were running out of IP addresses, are collectively called ipv4. The newer protocols, with essentially unlimited numbers of IP addresses, are called ipv6. Our new servers have been configured to accept both ipv4 and ipv6 connections transparently, so that you the user don't need to know which is in use at a particular time.
As a precaution, we have given additional names to our servers so you can specify whether ipv4 or ipv6 should be used. It's very unlikely that you will actually need to do so, unless you are a network administrator who is debugging either of these protocols.
Whenever you add a new domain via a control panel, your default website will always be configured to accept both ipv4 and ipv6 connections. You can tell which is which by the IP address that you see on the DNS management screen in your control panel. You can recognize ipv4 addresses because they are four numbers separated by dots. You can recognize ipv6 addresses because they are much longer and contain alphanumeric characters (a–f and 0–9) separated by colons.
Your website, by default, will have DNS entries for both ipv4 and ipv6 addresses.