Dynamic NAT can only be used to establish connections from within the private network out to the public network.
A pool of network addresses is maintained and used when an outbound connection is made. Each connection is assigned a unique public address. The maximum number of simultaneous connections is equal to the number of public addresses in the pool. This is similar to a one-to-one correspondence between addresses. Dynamic NAT allows you to communicate with the Internet through a dynamic NAT address. The following figure illustrates dynamic NAT.