is ipv6 backward compatible with ipv4?

Question

I\'ve got a little udp example program written using ipv4. If I alter the code to ipv6 would I still be able to communicate with anyone using the listener with an ipv4 address?

Answer 1

Not without the assistance of an IPv4/IPv6 gateway in the network, and even then communication will be limited by the typical problems introduced by network address translating gateways. The traditional advice for programmers facing decisions like this is to recommend supporting both IPv4 and IPv6 at the same time.