Question 700
A partner removes an old subnet from the VPN encryption policy but the branch keeps routing that prefix into the tunnel, producing blackholed traffic. Which FortiOS 7.6 configuration or corrective action is MOST appropriate?
Explanation
Correct Answer
Maintain site-to-site IPsec protected subnet coverage as network segments change, using compatible traffic selectors, routes and firewall policies for new or removed prefixes. This directly addresses the FortiOS configuration or response required by the case. Adding a new VLAN locally does not automatically extend remote IPsec selectors, route advertisements and firewall allow policies; each layer must agree. Verify with: Check remote and local subnet definitions, phase2 selectors, route advertisements, tunnel interface, policy group membership and packet traces for test traffic. Scenario: A partner removes an old subnet from the VPN encryption policy but the branch keeps routing that prefix into the tunnel, producing blackholed traffic.
Incorrect Answers
Integrate FortiGate IPsec tunnel interfaces into a supported SD-WAN steering design, ensuring underlay reachability, overlay routes and matching firewall policies for protected traffic. This addresses SD-WAN IPsec overlay routing and tunnel path choice, but not the principal task of the described flow. An SD-WAN member rule may select a physical underlay without providing the encrypted overlay route; policy, tunnel health and overlay steering are distinct dependencies. The better fit is: Maintain site-to-site IPsec protected subnet coverage as network segments change, using compatible traffic selectors, routes and firewall policies for new or removed prefixes. Scenario: A partner removes an old subnet from the VPN encryption policy but the branch keeps routing that prefix into the tunnel, producing blackholed traffic.
Select supported memory, local-disk, FortiAnalyzer or syslog destinations for the model and retention requirement, and detect loss of records before storage or forwarding limits are exceeded. This addresses FortiGate local log storage and reliable export, but not the principal task of the described flow. Some FortiGate models have no local log disk; memory-resident events are not durable archival storage, and choosing a collector without verifying ingestion is insufficient. The better fit is: Maintain site-to-site IPsec protected subnet coverage as network segments change, using compatible traffic selectors, routes and firewall policies for new or removed prefixes. Scenario: A partner removes an old subnet from the VPN encryption policy but the branch keeps routing that prefix into the tunnel, producing blackholed traffic.
Use the correct FortiGate traffic, UTM and system event logs with deliberate policy log settings and filters to explain session handling and threat actions. This addresses Policy traffic log interpretation and diagnostic event filtering, but not the principal task of the described flow. A UTM blocked-threat record and a firewall implicit-deny event are not interchangeable; absence of a traffic log may mean logging is disabled rather than that no packet arrived. The better fit is: Maintain site-to-site IPsec protected subnet coverage as network segments change, using compatible traffic selectors, routes and firewall policies for new or removed prefixes. Scenario: A partner removes an old subnet from the VPN encryption policy but the branch keeps routing that prefix into the tunnel, producing blackholed traffic.