[sk5t]

Kerberos and OAuth are examples of authentication protocols. LDAP is not principally designed for authentication, it is a protocol for reading and modifying an hierarchical directory service (think phone book, DNS, etc.), but the "LDAP bind" operation has often been pressed into service for authn.

[golangman]

It's probably just a typo, but OAuth(2) is exactly NOT an authentication protocol: https://oauth.net/articles/authentication/