Explanation
According to the SD-WAN 7.2 Study Guide, the SD-WAN overlay template simplifies the configuration of
IPsec tunnels in a hub-and-spoke topology. The template defines the following parameters:
type: dynamic for spokes, static for hubs
interface: the WAN interface to use for the IPsec tunnel
network-overlay: enable for spokes, disable for hubs
network-id: a unique identifier for each spoke
auto-discovery-sender: enable for hubs, disable for spokes
auto-discovery-receiver: enable for spokes, disable for hubs
Based on the exhibit, the FortiGate device has the following configuration:
type: dynamic
interface: port1
network-overlay: enable
network-id: 5
auto-discovery-sender: disable
auto-discovery-receiver: enable
Therefore, the FortiGate device is a spoke that establishes dynamic IPsec tunnels to the hub. It also has the
network-overlay and auto-discovery-receiver options enabled, which means it can send ADVPN shortcut
requests to other spokes when it receives a shortcut offer from the hub

ADVPN is a technology that allows dynamic creation of IPsec tunnels between branch sites without requiring pre-configured policies or keys. BGP is a routing protocol that can be used to exchange routes between ADVPN peers. IBGP is a type of BGP that runs between routers in the same autonomous system (AS), while EBGP is a type of BGP that runs between routers in different ASes. IBGP is preferred over EBGP for ADVPN, because IBGP preserves the next hop information of the routes, which is needed to establish the IPsec tunnels. EBGP changes the next hop information to the EBGP peer address, which may not be reachable by the ADVPN peers. Therefore, using IBGP for ADVPN avoids the need to configure additional static routes or redistribute routes between BGP and another routing protocol. Reference = ADVPN with BGP as the routing protocol, ADVPN, SD-WAN self-healing with BGP, Technical Tip: ADVPN with BGP as the routing protocol The statement that IBGP is preferred over EBGP for ADVPN because IBGP preserves next hop information (D) is true. In a typical ADVPN deployment, it's beneficial to maintain next hop information across the network to ensure proper routing and optimal path selection. Reference: This understanding comes from my knowledge of Fortinet's SD-WAN and ADVPN configurations, where BGP's behavior in terms of next hop preservation is a key consideration.

Performance SLA (Service Level Agreement) protocols are used in SD-WAN to monitor the quality and performance of various network services. The two protocols that specifically allow for verifying a specific value in the server response are:
* HTTP (Hypertext Transfer Protocol): HTTP is the foundation of data communication on the World Wide Web. It allows for fetching resources, such as HTML documents. You can configure an HTTP performance SLA to send specific requests (e.g., GET or POST) and then check if the response body contains a particular string or value. This is useful for validating web server functionality and content delivery.
* DNS (Domain Name System): DNS is responsible for translating domain names into IP addresses. A DNS performance SLA can be set up to query a specific domain and verify that the returned IP address or other DNS record values match what is expected. This helps ensure proper name resolution and accessibility of resources.