Which layer encodes and decodes data packets into bits and has two sub-layers?

Which layer encodes and decodes data packets into bits and has two sub-layers?

• A. Physical Layer
• B. Network Layer
• C. Presentation Layer
• D. Data Link Layer

Answer: (D)

Data Link Layer handles turning packets from the Network Layer into frames for transmission and defines two sublayers: Logical Link Control and Media Access Control. LLC manages how data is transferred over the link, including error checking and flow control, while MAC handles addressing and access to the shared medium. The actual encoding of frames into the physical signal is done by the Physical Layer, which converts frames into bits for transmission and decodes incoming bits back into frames. The combination of framing duties and the explicit two-sublayer structure makes this layer the correct choice. The Physical Layer focuses on signaling, the Network Layer on routing, and the Presentation Layer on data formatting and encryption, so they don’t match the two-sublayer framing role.

Data Link Layer handles turning packets from the Network Layer into frames for transmission and defines two sublayers: Logical Link Control and Media Access Control. LLC manages how data is transferred over the link, including error checking and flow control, while MAC handles addressing and access to the shared medium. The actual encoding of frames into the physical signal is done by the Physical Layer, which converts frames into bits for transmission and decodes incoming bits back into frames. The combination of framing duties and the explicit two-sublayer structure makes this layer the correct choice. The Physical Layer focuses on signaling, the Network Layer on routing, and the Presentation Layer on data formatting and encryption, so they don’t match the two-sublayer framing role.