A network administrator is deploying a Cisco IPS appliance and needs it to operate initially without affecting traffic flows. It must also collect data to provide a baseline of unwanted traffic before

Failsafe is a failure behavior that determines whether traffic is allowed or blocked when the IPS device becomes unavailable - it is not a passive monitoring mode for baselining.

Inline tap mode places the appliance physically inline in the traffic path and receives a copy for analysis, introducing a potential forwarding dependency that conflicts with the requirement to initially not affect traffic flows.

In promiscuous mode, the IPS sensor receives a copy of network traffic via a SPAN port or network tap and analyzes it without being in the forwarding path, so it cannot disrupt existing traffic flows. This allows the administrator to monitor and tune detection policies using real traffic data before reconfiguring the device for inline blocking mode.

Bypass mode allows traffic to pass through an inline IPS without inspection during maintenance or overload conditions - it is not a dedicated passive monitoring mode for collecting traffic baselines.