Question 720
After a firmware upgrade, one FTD peer offers only a different IKE encryption suite and IKE negotiation stops. Before changing security policy, what evidence should the engineer examine FIRST?
Explanation
Correct Answer
Inspect VPN event traces, IKE negotiation state, certificate or PSK errors, UDP 500/4500, and proposal mismatches. This checks the relevant condition before an engineer modifies production access or detection behavior. Tunnel establishment progresses through distinct authentication and negotiation stages; changing unrelated firewall rules cannot fix mismatched proposals. The controlled response would be: Diagnose VPN setup failures in phase order by comparing peer reachability, authentication identities, and mutually supported IKE and IPsec proposals. Situation: After a firmware upgrade, one FTD peer offers only a different IKE encryption suite and IKE negotiation stops.
Incorrect Answers
Inspect bidirectional security association counters, packet traces, NAT policy, route selection, and remote selectors. This evidence addresses FTD VPN up but no protected data; it would not establish the primary issue here. The diagnostic evidence needed for this scenario is: Inspect VPN event traces, IKE negotiation state, certificate or PSK errors, UDP 500/4500, and proposal mismatches. Situation: After a firmware upgrade, one FTD peer offers only a different IKE encryption suite and IKE negotiation stops.
Inspect SSH/HTTPS management services, NETCONF or RESTCONF configuration, model schema, access roles, and operation results. This evidence addresses NETCONF RESTCONF and API management security; it would not establish the primary issue here. The diagnostic evidence needed for this scenario is: Inspect VPN event traces, IKE negotiation state, certificate or PSK errors, UDP 500/4500, and proposal mismatches. Situation: After a firmware upgrade, one FTD peer offers only a different IKE encryption suite and IKE negotiation stops.
Inspect source/destination tuples, flow duration, byte counts, exporters, collector receipt, and sampling configuration. This evidence addresses NetFlow and telemetry flow analysis; it would not establish the primary issue here. The diagnostic evidence needed for this scenario is: Inspect VPN event traces, IKE negotiation state, certificate or PSK errors, UDP 500/4500, and proposal mismatches. Situation: After a firmware upgrade, one FTD peer offers only a different IKE encryption suite and IKE negotiation stops.


