Destination network address translation, or DNAT, is a kind of network address translation. In DNAT, technique of transparently changing the destination IP address of an en-route packet to another IP address, and changing it back on the reply to this packet. Any router situated between two endpoints can perform this transformation of the packet, but the packet must be altered upon both entry to the network and upon exit from the network.
DNAT is commonly used to publish a service from an internal network to a publicly accessible IP.
Dynamic Network Address Translation
Dynamic NAT, just like Static NAT, is not that common in smaller networks but you'll find it used within larger corporations with complex networks. The way Dynamic NAT differentiates from Static NAT is that where Static NAT provides a one-to-one internal to public static IP mapping, Dynamic NAT does the same but without making the mapping to the public IP static and usually uses a group of available public IPs.