Which of the following is an authentication protocol?

A.
Kerberos

B.
LDAP

C.
TLS

D.
PPTP

Explanation:
Kerberos is an industry standard authentication protocol used to verify user or host identity.
Kerberos v5 authentication protocol is the default authentication service for Windows 2000. It is
integrated into the administrative and security model, and provides secure communication between
Windows 2000 Server domains and clients.

Answer C is incorrect. Transport Layer Security (TLS) is an application layer protocol that uses a
combination of public and symmetric key processing to encrypt data.

Answer B is incorrect. Lightweight Directory Access Protocol (LDAP) is a protocol used to query and
modify information stored within directory services.

Answer D is incorrect. Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual
private networks. PPTP does not provide confidentiality or encryption. It relies on the protocol being
tunneled to provide privacy. It is used to provide secure, low-cost remote access to corporate
networks through public networks such as the Internet. Using PPTP, remote users can use PPPenabled client computers to dial a local ISP and connect securely to the corporate network through
the Internet. PPTP has been made obsolete by Layer 2 Tunneling Protocol (L2TP) and IPSec.