Identify the ONE CORRECT matching between the OSI layers and their…

2025

Identify the ONE CORRECT matching between the OSI layers and their corresponding functionalities as shown.

\(\begin{array}{|l|l|} \hline \textbf{OSI Layer} & \textbf{Functionality} \\ \hline (a) Network layer & (I) Packet routing \\ \hline (b) Transport layer & (II) Framing and error handling \\ \hline (c) Datalink layer & (III) Host to host communication \\ \hline \end{array} \)

  1. A.

    \((a)-(I), (b)-(II), (c)-(III) \)

  2. B.

    \((a)-(I), (b)-(III), (c)-(II)\)

  3. C.

    \((a)-(II), (b)-(I), (c)-(III)\)

  4. D.

    \((a)-(III), (b)-(II), (c)-(I)\)

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Correct answer: B

Correct matching: (a) → (I), (b) → (III), (c) → (II)

  • Network layer: Packet routing and logical addressing (selects paths for packets across networks).

  • Transport layer: End-to-end (host-to-host) communication, reliability, segmentation and flow control.

  • Datalink layer: Framing, link-level error detection and correction, and flow control on a physical link.

Why some mappings are incorrect:

  • Do not confuse framing (a link-level function) with end-to-end transport; framing belongs to the Datalink layer, while end-to-end reliability belongs to the Transport layer.

  • Packet routing across networks is the responsibility of the Network layer, not the Transport or Datalink layers.

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