CCNA Routing and Switching (legacy) — Question 177

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

Answer options

• A. X.25
• B. HDLC
• C. PPP
• D. Frame Relay

Correct answer: C

Explanation

The correct answer is PPP because it is designed to support both synchronous and asynchronous circuits, and it includes built-in security mechanisms like encryption. X.25 is primarily for packet-switched networks and does not include security features. HDLC is a bit-oriented protocol but lacks the extensive security options of PPP, and Frame Relay does not provide native security mechanisms.