An administrator is investigating a security incident where a workstation is communicating with a known command and control (C2) server. The FortiGate has IPS enabled but did not block the traffic. Which TWO configuration issues could explain why the IPS did not detect the C2 communication? (Choose two.)
Without SSL inspection, encrypted C2 traffic is invisible to IPS.
Why this answer
Without SSL deep inspection, the FortiGate cannot decrypt HTTPS traffic to inspect the payload for C2 signatures. IPS operates on decrypted content; if the C2 communication uses TLS, the IPS engine only sees encrypted packets and cannot match application-layer signatures. Enabling SSL deep inspection with a valid CA certificate is required to decrypt and inspect the traffic.
Exam trap
The trap here is that candidates often assume 'Inline' mode or 'Transparent' mode inherently affect detection capability, when in fact they only affect traffic flow or logging, not the IPS engine's ability to inspect decrypted content.