In AOS-CX switches, which protocol is primarily used for device discovery and configuration?

The correct choice revolves around the function of the Link Layer Discovery Protocol (LLDP), which plays a critical role in network management by facilitating device discovery. LLDP is a Layer 2 protocol used to allow network devices to advertise their identity and capabilities to other nodes on the network.

In the context of AOS-CX switches, LLDP is instrumental in simplifying network management and configuration. When devices utilize LLDP, they can exchange information about themselves, such as their port identifiers, capabilities, and their neighbors, thereby allowing for easier topological mapping of the network. This automated discovery helps network administrators effectively monitor and manage their network infrastructure without extensive manual intervention.

The other protocols listed serve different purposes. Spanning Tree Protocol (STP) is primarily used for preventing loops in network topologies by managing the paths between switches. Virtual LAN Protocol (VLAN) relates to segmenting network traffic into distinct networks to improve performance and security but does not handle device discovery. Simple Network Management Protocol (SNMP) is utilized for managing devices on IP networks but does not specifically focus on device discovery as LLDP does. Thus, LLDP is uniquely suited for the task described in the question, making it the correct answer.