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CISSP · Question #869

In the Open System Interconnection (OSI) model, which layer is responsible for the transmission of binary data over a communications network?

The correct answer is B. Physical Layer. The OSI model divides network communication into seven layers, each with a distinct responsibility. The Physical Layer (Layer 1) is specifically responsible for transmitting raw binary data as electrical, optical, or radio signals over a physical medium.

Submitted by thandi_sa· Mar 5, 2026Communication and Network Security

Question

In the Open System Interconnection (OSI) model, which layer is responsible for the transmission of binary data over a communications network?

Options

  • AApplication Layer
  • BPhysical Layer
  • CData-Link Layer
  • DNetwork Layer

How the community answered

(33 responses)
  • A
    3% (1)
  • B
    91% (30)
  • C
    6% (2)

Why each option

The OSI model divides network communication into seven layers, each with a distinct responsibility. The Physical Layer (Layer 1) is specifically responsible for transmitting raw binary data as electrical, optical, or radio signals over a physical medium.

AApplication Layer

The Application Layer (Layer 7) provides network services directly to end-user applications such as HTTP, FTP, and DNS, and is not involved in the physical transmission of binary data.

BPhysical LayerCorrect

The Physical Layer (Layer 1) of the OSI model is responsible for the transmission and reception of raw binary data (bits) over a physical communication medium such as copper wire, fiber optic cable, or wireless radio frequencies. It defines the electrical, mechanical, and procedural specifications for activating, maintaining, and deactivating physical connections. This layer deals with voltage levels, timing, bit rates, and physical connectors, making it the sole layer concerned with raw binary transmission.

CData-Link Layer

The Data-Link Layer (Layer 2) is responsible for node-to-node data transfer and error detection/correction in frames between directly connected nodes, not the raw binary transmission over the physical medium.

DNetwork Layer

The Network Layer (Layer 3) handles logical addressing and routing of packets between different networks (e.g., IP addressing), and does not deal with the physical transmission of binary signals.

Concept tested: OSI model Physical Layer binary data transmission

Source: https://learn.microsoft.com/en-us/windows-server/networking/technologies/nic-teaming/osi-model

Topics

#OSI model#physical layer#data transmission#network fundamentals

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