What failure mode should an IT manager configure for an intrusion prevention system (IPS) to ensure traffic flow continues if it fails?

Configuring an intrusion prevention system (IPS) to use a fail-open mode allows traffic to flow uninterrupted even in the event of a failure. This is particularly important for environments where maintaining network availability is crucial. In fail-open mode, if the IPS encounters an error or goes down, it does not block any network traffic, thereby minimizing disruptions to business operations. This choice ensures that legitimate users can continue to access the network without interruption, even if there is a potential threat that the IPS would normally mitigate.

In contrast, a fail-safe mode might cause the system to block all traffic during a failure, which could lead to significant downtime and disrupt legitimate business functions. Fail-closed would mean traffic is halted until the IPS is operational again, which again would not be favorable for operational continuity. Fail-silent typically means that the system stops reporting but might not actively block traffic, leading to ambiguities in how traffic is handled.

Therefore, selecting fail-open provides the most practical solution for ensuring continuous traffic flow during IPS failures while still allowing for proper monitoring and control when the system is functioning correctly.