Question 250
Two switches negotiate mismatched speed and duplex after a port replacement, and intermittent drops look like firewall policy denials until physical error counters are checked. Which diagnostic evidence should the FortiGate administrator check FIRST?
Explanation
Correct Answer
Check link speed and duplex, ARP entries, ingress and egress interfaces, route choice, debug-flow policy messages, packet captures and session flags. This distinguishes the relevant FortiGate device, session or controller evidence. A ping from the FortiGate control plane may use a different source and route than user traffic; overbroad live debug capture can also expose sensitive packets or strain production. The corresponding action is: Trace a permitted test flow using FortiOS interface status, routing tables, packet sniffers, session tables and narrowly scoped debug flow, then stop diagnostics safely. Scenario: Two switches negotiate mismatched speed and duplex after a port replacement, and intermittent drops look like firewall policy denials until physical error counters are checked.
Incorrect Answers
Compare FortiGate CNF onboarding, cloud account permissions, policy targets, networking integration, logging endpoints, deployment region and licensed service scope. This diagnostic is related to FortiGate cloud-native firewall CNF service responsibility rather than the controlling evidence for this scenario. Examine instead: Check link speed and duplex, ARP entries, ingress and egress interfaces, route choice, debug-flow policy messages, packet captures and session flags. Scenario: Two switches negotiate mismatched speed and duplex after a port replacement, and intermittent drops look like firewall policy denials until physical error counters are checked.
Examine diagnose sys top or equivalent supported process views, CPU load by core, session throughput, UTM process consumption, interrupts and incident timestamps. This diagnostic is related to CPU process health and abnormal-load troubleshooting rather than the controlling evidence for this scenario. Examine instead: Check link speed and duplex, ARP entries, ingress and egress interfaces, route choice, debug-flow policy messages, packet captures and session flags. Scenario: Two switches negotiate mismatched speed and duplex after a port replacement, and intermittent drops look like firewall policy denials until physical error counters are checked.
Examine session-pickup configuration, cluster synchronization, monitored-link state, active sessions, NAT state, failover timing and traffic results. This diagnostic is related to HA session-pickup and failover continuity rather than the controlling evidence for this scenario. Examine instead: Check link speed and duplex, ARP entries, ingress and egress interfaces, route choice, debug-flow policy messages, packet captures and session flags. Scenario: Two switches negotiate mismatched speed and duplex after a port replacement, and intermittent drops look like firewall policy denials until physical error counters are checked.