Which Layer 2 protocol encapsulation type supports synchronous and asynchronous circuits and
has built-in security mechanisms?

A.
HDLC

B.
PPP

C.
X.25

D.
Frame Relay

Explanation:
PPP: Provides router-to-router and host-to-network connections over synchronous and
asynchronous circuits. PPP was designed to work with several network layer protocols, including
IP. PPP also has built-in security mechanisms, such as Password Authentication Protocol (PAP)
and Challenge Handshake Authentication Protocol (CHAP).