What fallback method does an AP use if the first discovery attempt fails?

In the context of Aruba access points (APs), when the initial attempt to discover a controller fails, the AP resorts to DHCP Option 43 as a fallback method. This option is used to provide the controller's IP address through DHCP messages. When an AP connects to a network, it typically uses various methods to discover the controller, with ADP (Aruba Discovery Protocol) being the primary method. However, if the ADP multicast or broadcast method does not yield a response—possibly due to network configurations, firewall settings, or other reasons—the AP can utilize DHCP Option 43.

In this scenario, Option 43 allows the AP to retrieve necessary configuration information including the IP address of the controller it should connect to, thereby enabling the AP to join the network and function properly. This fallback is crucial for ensuring that the AP can still operate even in less-than-ideal network conditions, allowing for more robust and flexible network deployment.