In firewall management, what challenge involves the inability to effectively monitor all systems?

The challenge identified as a lack of visibility is crucial in firewall management because it refers to the difficulty in having a comprehensive view of the entire network environment, including all connected devices, traffic patterns, and potential security incidents. When organizations cannot effectively monitor all systems, they may miss critical alerts, fail to recognize unusual activities, and become less aware of vulnerabilities present in their infrastructure. This limited visibility can result in the inability to enforce security policies properly and respond to threats in a timely manner.

While inadequate hardware, poor network design, and high costs can certainly impact network security to some extent, they don't specifically refer to the challenges of visibility in monitoring all systems. Inadequate hardware might hinder performance, poor network design could lead to inefficiencies, and high costs may restrict budget allocations for security initiatives, but they do not pinpoint the issue of not being able to monitor the network comprehensively. Thus, the lack of visibility is identified as the core challenge that directly relates to monitoring capabilities in firewall management.