What was the motivation for adding the IPV6_V6ONLY flag?

Question

In IPv6 networking, the IPV6_V6ONLY flag is used to ensure that a socket will only use IPv6, and in particular that IPv4-to-IPv6 mapping won\'t be used for that socket. On many

Answer 1

Imagine a protocol that includes in the conversation a network address, e.g. the data channel for FTP. When using IPv6 you are going to send the IPv6 address, if the recipient happens to be a IPv4 mapped address it will have no way of connecting to that address.