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Difficulty: MediumOSI Model Layers and Functions

A network technician is configuring traffic inspection policy on a next-generation firewall to monitor operations occurring specifically at Layer 4 of the OSI model. Which of the following primary functions takes place at this layer of the OSI model?

  1. Segmenting data streams from higher layers and providing optional connection-oriented reliability or flow control.Answer
  2. B
    Encrypting, compressing, and translating data structures into a standardized format readable by the application.
  3. C
    Determining the optimal path across interconnected networks using logical IP addressing to route packets.
  4. D
    Packaging raw binary bits into discrete frames and handling node-to-node MAC address delivery over local media.

Answer

Segmenting data streams from higher layers and providing optional connection-oriented reliability or flow control.
The correct option highlights the fundamental duties of the Transport Layer (Layer 4). Layer 4 is responsible for breaking upper-layer application data into manageable segments, reassembling them at the destination, and managing mechanisms such as flow control, sequence numbering, and error recovery (via protocols like TCP).

Step-by-Step Solution

1
Identify the requested OSI layer from the question stem.
The target layer specified is Layer 4 (the Transport Layer).
The firewall rule context requires identifying the exact functional boundary of Layer 4.
2
Analyze the functional responsibilities of Layer 4.
Layer 4 handles end-to-end transport functions such as segmentation, flow control, multiplexing via port numbers, and optional connection reliability (e.g., TCP acknowledgments).
This establishes the core operation separating transport functions from lower physical/network routing layers and upper presentation/application layers.
3
Evaluate the option descriptions to select the correct functional matching.
The selection describing segmentation of data streams and flow control correctly matches Layer 4 functions.
All other options describe operations belonging to Layer 6 (Presentation), Layer 3 (Network), and Layer 2 (Data Link).

Key Concept

OSI Layer 4 (Transport Layer) Functions
Estimated Time:1m 0s
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Topics

OSI Model Layers and Functions

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