Which identity source allows Cisco ISE to look for a user or MAC address without authentication being performed?

The identity source that allows Cisco ISE to look for a user or MAC address without requiring authentication is LDAP (Lightweight Directory Access Protocol). LDAP is designed to provide a means to access and maintain distributed directory information services over an Internet Protocol (IP) network. In the context of Cisco ISE, LDAP can be utilized to query and retrieve user or device information based on attributes such as user names or MAC addresses without the need for initiating an authentication session.

This capability is particularly useful for scenarios like device profiling or when identifying users through their MAC addresses in a network. By accessing the information stored in an LDAP directory, Cisco ISE can effectively determine the identity of devices or users to apply appropriate policies, even before the actual authentication process is initiated.

The other options, such as RADIUS, SAML, and TACACS+, are primarily focused on authentication processes. RADIUS and TACACS+ specifically serve as authentication protocols, while SAML is used for federated authentication scenarios. In these cases, an authentication event is necessary to verify the identity of the user or device, contrasting with LDAP's ability to look up information without prior authentication.