Difficulty: Easy
Correct Answer: The transport layer provides for any format, translation or code conversion necessary to put the data into an intelligible format.
Explanation:
Introduction / Context:
The OSI model separates concerns so that each layer has clear responsibilities. Distinguishing between the Presentation layer (format/translation) and the Transport layer (end-to-end delivery) helps avoid common misconceptions when mapping protocols and services to layers.
Given Data / Assumptions:
Concept / Approach:
Presentation (Layer 6) is responsible for data representation: character set translation, encryption/decryption, compression, and syntax marshaling. Transport (Layer 4) provides end-to-end delivery services: segmentation, sequencing, flow and error control, and retransmission. Data Link (Layer 2) manages framing and reliable transfer across a local link between adjacent nodes.
Step-by-Step Solution:
Compare option (a) with the OSI definitions: its functions belong to Presentation, not Transport.Confirm option (b) correctly describes the Presentation layer.Confirm option (c) correctly captures the Data Link layer’s responsibility.Therefore, (a) is the incorrect statement.
Verification / Alternative check:
Mapping to real protocols: TLS record encoding and content-encoding transformations align with Presentation-layer concepts; TCP’s sequencing and congestion control exemplify Transport-layer duties.
Why Other Options Are Wrong:
“All of the above”: Not true because (b) and (c) are correct.
Common Pitfalls:
Attributing encryption and data format conversion to Transport; while some stacks blur layers, in OSI these are Presentation functions.
Final Answer:
The transport layer provides for any format, translation or code conversion necessary to put the data into an intelligible format.
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