 The originating host may perform Maximum transmission unit (MTU) path discovery to determine the packet size that can be transmitted without fragmentation, and then set the "don't fragment" (DF) bit in the appropriate packet header field.Of course, this is only a one-way solution, because the responding host can send packets of any size, which may be fragmented before reaching the NAT.Destination network address translation (DNAT) is a technique for transparently changing the destination IP address of an end route packet and performing the inverse function for any replies.