When used as part of a WLAN authentication solution, what is the role of LDAP?

A data retrieval protocol used by an authentication service such as RADIUS

An IEEE X.500 standard compliant database that participates in the 802.1X port-based access control process

A SQL compliant authentication service capable of dynamic key generation and distribution

A role-based access control protocol for filtering data to/from authenticated stations.

An Authentication Server (AS) that communicates directly with, and provides authentication for, the Supplicant.