Cisco Certified Network Associate (CCNA) Practice Exam

What are the two control protocols of PPP at layer 2 and layer 3?

1. Link Control Protocol (LCP) and Point-to-Point Protocol (PPP)

2. Network Control Protocol (NCP) and Layer Control Protocol (LCP)

3. Link Control Protocol (LCP) and Network Control Protocol (NCP)

4. Data Link Control (DLC) and Network Control Protocol (NCP)

The correct answer is: Link Control Protocol (LCP) and Network Control Protocol (NCP)

The correct answer highlights two key protocols utilized in the Point-to-Point Protocol (PPP) framework, specifically the Link Control Protocol (LCP) and the Network Control Protocol (NCP). LCP operates at layer 2 of the OSI model, facilitating the establishment, configuration, maintenance, and termination of the PPP link. It is responsible for negotiating options such as maximum transmission unit (MTU) size, authentication methods, and other link parameters, enabling devices to agree on how to communicate effectively over the link. NCP, functioning at layer 3, allows for the encapsulation of multiple network layer protocols over the PPP connection. It enables the negotiation and configuration of various network layer protocols, such as IP, IPX, and AppleTalk. Essentially, NCP is tasked with handling the specifics of how different network layer protocols can traverse the established PPP link. This combination of LCP and NCP is essential for PPP to provide a versatile and manageable point-to-point communication method, making it successful in diverse networking environments. Thus, the identification of LCP as the layer 2 control protocol and NCP as the layer 3 control protocol is vital to understanding how PPP operates in real-world network scenarios.