Dynamic Address-Only Source Translation Overview
With dynamic address-only translation, you can map a private IP source address to a public IP address. A public address is picked up dynamically from a source NAT pool, and the mapping from the original source address to the translated source address is maintained as long as there is at least one active flow that uses this mapping. The port is not mapped.
Benefits of Dynamic Address-Only Source Translation
Allows hosts in the private network to connect with the external domain, while hiding the private network.
Allows a few public IP addresses to be used by several private hosts