Authentication in Active Directory

NTLM authentication

It is a challenge-response mechanism:

1. >The user sends their username and password to the server.
2. >The server responds with a challenge.
3. >The user responds with the challenge and a response to the challenge.
4. >The server forwards the user-sent challenge and response to the domain controller.
5. >The domain controller verifies the response against a database.
6. >If the response is valid, the domain controller tells the server to allow the user to access the service.
7. >If the response is invalid, the domain controller denies the user's request.

Kerberos authentication

It is a ticket-based authentication method.