To solve this high CPU usage scenario involving the ipsengine, we must understand the specific functions of the diagnose test application ipsmonitor commands shown in the troubleshooting steps.
Analyze the Situation:
Exhibit: The diagnose sys top output shows the ipsengine process is in a run state (R) consuming 99% CPU.
Previous Action: The administrator already ran diagnose test application ipsmonitor 5.
Result: The CPU usage did not drop.
Understand the Commands:
diagnose test application ipsmonitor 5: This command toggles IPS Bypass Mode. When enabled, the IPS engine lets traffic pass through without inspection.
Implication: If the CPU was high due to traffic volume, enabling bypass would drop the CPU load immediately.
Failure: Since the CPU remained at 99% after bypass, the ipsengine process is likely frozen, stuck, or in an internal infinite loop unrelated to the current traffic flow. The process itself is the problem, not the traffic volume.
Evaluate the Solution (Option B):
diagnose test application ipsmonitor 2: This command toggles the IPS engine's Enable/Disable status.
Because the engine is stuck (bypass failed to relieve pressure), the "Immediate action" required is to stop or restart the process entirely.
Running option 2 effectively disables/kills the stuck IPS engine instance, which will immediately drop the CPU usage to near zero. (It can then be toggled again to restart it).
Why other options are incorrect:
A (Reduce signatures): This is a tuning measure for normal operation, not an immediate fix for a stuck process at 99% CPU.
C (Disable IPS on policies): This is a configuration change that takes time and requires a commit; it is not the most immediate diagnostic tool available.
D (Bypass all IPS engines): This describes the action of command 5 (Bypass), which the prompt explicitly states was already performed and failed.
[Reference:, FortiGate Security 7.6 Study Guide (IPS & Diagnostics): "Troubleshooting IPS high CPU: 1. Check top. 2. Try bypass (ipsmonitor 5). 3. If CPU persists, restart the engine (ipsmonitor 99 or 2).", , , ]