Check Point Certified Security Administrator (CCSA) Practice Exam

Which type of NAT uses a single public IP address for multiple hosts?

1. Static NAT.

2. Dynamic NAT.

3. Port Address Translation (PAT).

4. Policy NAT.

The correct answer is: Port Address Translation (PAT).

Port Address Translation (PAT), often referred to as NAT overload, allows multiple hosts on a local network to be mapped to a single public IP address while using different port numbers to distinguish between the connections. This technique is particularly useful in environments where the number of available public IP addresses is limited, enabling many devices to access the internet simultaneously without needing a unique public IP for each one. With PAT, when a device sends out a request to the internet, the NAT device translates the source IP address into the public IP and assigns a unique source port number for that connection. When the response is received, the NAT device uses the port number to identify which local host should receive the reply. This method maximizes the efficient use of available public IP addresses and provides cost-effective network connectivity. In contrast, Static NAT maps a single private IP address to a single public IP address one-to-one, and Dynamic NAT assigns a public IP address from a pool to a private IP address temporarily but requires at least one public IP for each private IP in use. Policy NAT is more complex and based on rules, but does not focus primarily on the conservation of IP addresses in the same way that PAT does.