Which of the following best describes NAT’s role in network security?

NAT, or Network Address Translation, plays a vital role in enhancing network security primarily through the mechanism of IP address masking. By translating private IP addresses within a local network to a single public IP address, NAT effectively conceals the internal unit’s actual IP addresses. This process prevents external devices from directly accessing the internal network structure, making it more challenging for potential attackers to target specific devices or services.

Additionally, NAT serves to restrict the visibility of the internal network from the outside world, thereby adding a layer of security. Whenever a packet wants to leave the internal network, NAT translates the source IP address to the public IP, and when a response comes back, NAT translates it back to the respective internal IP. This translates into a barrier for unauthorized access attempts, as external entities cannot see or reach the private addresses directly.

In contrast, encryption secures the data that's sent over the network but does not influence how addresses are exposed. Public key infrastructure is focused on management and distribution of encryption keys for secure communication. Traffic filtering pertains to controlling what data packets are allowed or blocked based on rules, which is a different aspect of network security. Therefore, IP address masking through NAT is primarily what enhances security in the context of this question.