John has implemented________in the network to restrict the limit of public IP addresses in his...

 Network Address Translation (NAT) is a network function that translates private IP addresses into a public IP address. This technique restricts the number of public IP addresses required by an organization, as multiple devices on a private network can share a single public IP address. NAT also enhances firewall filtering techniques by hiding the internal IP addresses from the external network, which adds a layer of security by making it more difficult for attackers to target specific devices within the organization’s network. It is a common practice in network security to use NAT in conjunction with firewalls to manage the traffic entering and leaving the network, ensuring that only authorized access is permitted.

References: The information provided aligns with the Certified Network Defender (CND) program’s focus on network defense fundamentals, including the application of network security controls like NAT12. Additionally, NAT’s role in conserving IP addresses and providing security by hiding internal network addresses is well-documented and is part of the network security best practices345.