NAT and PAT

PAT is a type of dynamic NAT through which address translation can be configured at the port level. It maps multiple source local addresses and ports to a single global IP address and port from a pool of IP addresses that are routable on the destination network. In PAT, the interface IP address is used in combination with the port number and multiple hosts could have same IP address because the port number is unique.

Key Differences between NAT and PAT

• PAT is a form of dynamic NAT
• NAT uses IP addresses in the process of translation whereas PAT uses IP addresses along with port numbers.
• NAT is used to map public IP addresses to private IP addresses. This could be a one-to-one or many-to-one relation.
• PAT maps multiple private IP addresses into a single public IP (many-to-one) by using ports