Fortinet Exam NSE7_PBC-7.2 Topic 2 Question 23 Discussion

Spoke VPC Routing:The 0.0.0.0/0 (default) route in the spoke VPC must point to the Transit Gateway attachment for traffic to reach other VPCs or external destinations.

Security VPC Routing:Traffic from the security VPC needs to pass through the FortiGate for inspection and security controls. Therefore, the 0.0.0.0/0 route in the security VPC's TGW subnet routing table must point to the FortiGate's internal port.

FortiGate Routing:The FortiGate's internal subnet must have its 0.0.0.0/0 route configured to point to the Transit Gateway attachment, allowing traffic to be returned to other VPCs or reach the internet.

In an SD-WAN TGW Connect topology, when routing traffic from a spoke VPC to a security VPC through a Transit Gateway, the mandatory initial steps include:

From the spoke VPC internal routing table, point 0.0.0.0/0 traffic to the TGW (Option A): This step is crucial for ensuring that all traffic from the spoke VPC destined for external networks is directed through the Transit Gateway, allowing for centralized management and security inspection.

From the security VPC TGW subnet routing table: point 0.0.0.0/0 traffic to the FortiGate internal port (Option B): Routing all traffic from the TGW subnet in the security VPC to the FortiGate's internal port ensures that traffic is subjected to the necessary security policies and inspections provided by the FortiGate appliance before it proceeds to other destinations or returns to the spoke VPCs.

From the security VPC FortiGate internal subnet routing table, point 0.0.0.0/0 traffic to the TGW (Option D): This configuration ensures that traffic returning from the security processes handled by the FortiGate is routed back through the Transit Gateway, maintaining the integrity of the secure transit path and ensuring proper routing back to the originating spoke or onward to the internet.