PPP Layer in the OSI Model

C

PPP stands for Point-to-Point Protocol, and it's a data link layer protocol used for establishing and maintaining a direct connection between two nodes or devices. PPP is primarily used for connecting a computer or router to an internet service provider (ISP) through a telephone line or other communication channels.

PPP operates at the Data Link Layer, which is layer 2 of the OSI model. The data link layer is responsible for providing error-free and reliable data transfer between nodes on the same physical network.

PPP encapsulates data frames and adds a header and trailer to the frame, making it possible to transmit the frame over a point-to-point link. PPP's header includes control information, such as protocol identification, frame sequence numbers, and error detection codes.

PPP supports multiple network layer protocols, including IP (Internet Protocol), IPX (Internetwork Packet Exchange), and AppleTalk. When PPP is used with IP, it's commonly referred to as PPPoE (PPP over Ethernet) or PPPoA (PPP over ATM).

Therefore, the correct answer is C. Layer 2.