Some of the Destination Unreachable codes for ICMPv4 are as follows:
0 - Net unreachable
1 - Host unreachable
2 - Protocol unreachable
3 - Port unreachable
Some of the Destination Unreachable codes for ICMPv6 are as follows:
0 - No route to destination
1 - Communication with the destination is administratively prohibited (e.g., firewall)
2 – Beyond scope of the source address
3 - Address unreachable
4 - Port unreachable