Which of the following authentication types is used primarily to authenticate users through the use of tickets?

LDAP is a directory access protocol used to query and modify directory services, not a ticket-based authentication system.

RADIUS is an AAA protocol that authenticates via a challenge-response mechanism using shared secrets, not tickets.

TACACS+ is a Cisco-proprietary AAA protocol that separates authentication, authorization, and accounting using TCP, but does not use a ticket-based model.

Kerberos authenticates users by issuing a Ticket Granting Ticket (TGT) from the Authentication Server, which is then used to request service tickets from the Ticket Granting Server without re-entering credentials. The ticket-based approach means passwords are never sent over the network, and tickets expire to limit replay attack windows. This ticket architecture is the defining characteristic that distinguishes Kerberos from other authentication protocols.