Which of the following is NOT a host-based solution for detecting or preventing malicious code operations?

The option that is not a host-based solution for detecting or preventing malicious code operations is network boundary firewalls. Host-based solutions are typically implemented on individual devices, focusing on protecting and managing security at the endpoint level, such as computers and servers.

Anti-virus software is designed specifically to identify, isolate, and eliminate malicious software on host machines. Memory management utilities can also play a role in optimizing system performance, but they often include features that help detect and mitigate the effects of malicious code. Host-based monitoring tools analyze system activity in real time, looking for suspicious behavior or anomalies that could indicate a security threat.

In contrast, network boundary firewalls protect an entire network by monitoring and controlling incoming and outgoing network traffic based on predetermined security rules. They are positioned at the perimeter of the network, functioning to filter traffic before it reaches individual hosts, rather than being specifically tied to the host's internal operations. Thus, they do not fall under the category of host-based solutions.