I tried to convert the destination address to IPv6 format as ::ffff:IPv4. And use a socket of AF_INET6 type. It gives error: Network Unreachable. But using the same technique I am able to communicate from IPV4 to IPV6
Thanks for your help in advance.
IPv4 and IPv6 are separate protocols. They don't talk to each other.
On some operating systems you can use an IPv6 socket and accept incoming IPv4 connections on it. But that is just a software thing to make code development easier for server code. I have never seen that work for client code. You'll have to create the right socket type for that.
Usually you resolve a hostname using DNS, you'll get multiple answers (IPv4 and IPv6), you iterate over them creating the required socket type and try to connect. If it works you use that socket, if not you do the next iteration which creates a new socket etc.
If you code that is sensitive to delays you might want to implement the happy eyeballs algorithm.
::ffff:192.0.2.1 style addresses, but that is just software masquerading. It is still an IPv4 connection on the wire.On most systems, PF_INET6 sockets are able to communicate with IPv4 addresses by using addresses in the ::FFFF:0:0/96 range. However, this is only done at the level of the sockets library: the actual on-the-wire data are plain IPv4 packets (as though you had used an PF_INET socket), there is no protocol conversion in the network.
The error you receive indicates that you have no IPv4 route to the requested destination. This probably indicates that your host doesn't have an IPv4 default route. There is no solution to that — without IPv4 connectivity, there is nothing you can do to reach an IPv4 address.
