Question 910
Two office FTD peers establish an IKE session but an application subnet is absent from the protected traffic definition. Which Cisco security control or operational response BEST addresses the stated need?
Explanation
Correct Answer
Configure FTD site-to-site VPN using compatible peer parameters, network selectors, identities, and routing/access rules, then verify both tunnel phases. This control addresses the failure mechanism and narrows the enforcement boundary. Successful VPN peer authentication does not prove application forwarding; selectors, route tables, NAT, and access policies also govern data traffic. Confirm pre-change conditions using: Inspect peer public addresses, IKE/IPsec proposals, NAT treatment, interesting traffic, and security association counters. Situation: Two office FTD peers establish an IKE session but an application subnet is absent from the protected traffic definition.
Incorrect Answers
Configure Cisco Secure Client remote access to FTD with supported authentication, client profile, access restrictions, and split tunnel settings. This response applies to Cisco Secure Client remote VPN policy, not the controlling requirement in this case. Remote client tunnel success, user authentication, and authorized application reachability are distinct troubleshooting checkpoints. For this scenario, the targeted action is: Configure FTD site-to-site VPN using compatible peer parameters, network selectors, identities, and routing/access rules, then verify both tunnel phases. Situation: Two office FTD peers establish an IKE session but an application subnet is absent from the protected traffic definition.
Enable DHCP snooping on the supported switch VLANs and trust only intended DHCP-server-facing interfaces. This response applies to DHCP snooping trust and rogue server control, not the controlling requirement in this case. DHCP snooping distinguishes trusted DHCP infrastructure from untrusted access ports and creates bindings useful for other Layer 2 controls. For this scenario, the targeted action is: Configure FTD site-to-site VPN using compatible peer parameters, network selectors, identities, and routing/access rules, then verify both tunnel phases. Situation: Two office FTD peers establish an IKE session but an application subnet is absent from the protected traffic definition.
Trace FTD VPN encryption/decryption counters, routes, NAT exemptions, and ACL matching when IKE is up but applications fail. This response applies to FTD VPN up but no protected data, not the controlling requirement in this case. IKE-up status validates part of the control plane; the protected data plane requires matching routes, selectors, and NAT behavior. For this scenario, the targeted action is: Configure FTD site-to-site VPN using compatible peer parameters, network selectors, identities, and routing/access rules, then verify both tunnel phases. Situation: Two office FTD peers establish an IKE session but an application subnet is absent from the protected traffic definition.


