Refer to the exhibit, which shows a corporate network and a new remote office network.

In this scenario, the corporate network and the new remote office network need to communicate over the Internet, which requires a secure and dynamic routing method. Since both networks are using OSPF (Open Shortest Path First) as the routing protocol, the best approach is to establish an OSPF over IPsec VPN to ensure secure and dynamic route propagation.

OSPF is already running on the corporate network, and extending it over an IPsec tunnel allows dynamic route exchange between the corporate FortiGate and the remote office FortiGate. IPsec provides encryption for traffic over the Internet, ensuring secure communication. OSPF over IPsec eliminates the need for manual static routes, allowing automatic route updates if networks change.

The new remote office's 192.168.1.0/24 subnet will be advertised dynamically to the corporate network without additional configuration.