Dynamic PAT Disadvantages and Advantages
Dynamic PAT lets you use a single mapped address, thus conserving routable addresses. You can even use the threat defense device interface IP address as the PAT address.
You cannot use dynamic PAT for IPv6 (NAT66) when translating between interfaces in the same bridge group. This restriction does not apply when the interfaces are members of different bridge groups, or between a bridge group member and a standard routed interface.
Dynamic PAT does not work with some multimedia applications that have a data stream that is different from the control path. For more information, see NAT Support for Inspected Protocols.
Dynamic PAT might also create a large number of connections appearing to come from a single IP address, and servers might interpret the traffic as a DoS attack. You can configure a PAT pool of addresses and use a round-robin assignment of PAT addresses to mitigate this situation.