On 07/12/10 13:22, John Thomas wrote: > Can a machine with only an IPV6 address communicate with a machine that > only has an IPV4 or are they separate? They are separated. It's two different protocols, even though they are similar in many aspects. There are some projects trying to bridge that for single-stack IPv6 networks. But I've concluded running dual-stack with both IPv4 and IPv6 is less error prone, as such a proxy solutions will not always work 100% perfect. The IPv4 addresses needs to be translated into a IPv6 addresses by a local DNS service, and the proxy anyway need IPv4 access to reach the IPv4 host. David S.