Is the person who is attempting to log on really who they say they are? What form of access control does this questions stem from?

Authorization determines what an authenticated user is permitted to do or access, rather than verifying their identity.

Authentication is the security process that confirms a user's claimed identity by validating credentials like usernames, passwords, biometrics, or security tokens.

Kerberos is an authentication protocol, but 'Authentication' is the broader concept describing the identity verification process itself.

Mandatory Access Control (MAC) is a type of access control model where access rights are governed by system-wide rules and security labels, not the initial identity verification process.